Attachment G Geotechnical Report

ATTACHMENT G GEOTECHNICAL REPORT

Geotechnical Engineering Report Avon Wastewater Treatment Facility Nutrient Upgrades Project Avon, Colorado March 2019

March 27, 2019 File Number: 517050-000

Carollo Engineers, Inc. 390 Interlocken Crescent, Suite 800 Broomfield, CO 80021

Attention: Jeff Berlin, P.E.

Subject: Geotechnical Engineering Report Avon Wastewater Treatment Facility Nutrient Upgrades Project Avon, Colorado

Mr. Berlin:

Submitted herewith is the geotechnical engineering report for the Avon Wastewater Treatment Facility Nutrient Upgrades Project. This study was conducted in accordance with the contract between Brierley Associates and Carollo Engineers, Inc. This report contains the results of our findings, an engineering interpretation with respect to the available project characteristics, and recommendations to aid design and construction of earth-related phases of this project.

We appreciate the opportunity to work with you on this project. If we can be of further assistance, or if you have any questions, please contact our office.

Sincerely, BRIERLEY ASSOCIATES

3/27/19

Derek Magnuson, PG, CEG Steven Kuehr, PE Project Geologist Principal

990 South Broadway, Suite 222, Denver, CO 80209 | 303-703-1405 | www.BrierleyAssociates.com Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page i of ii TABLE OF CONTENTS

1 Introduction ...... 1 2 Site Description ...... 2 3 Project Description ...... 2 4 Field and Laboratory Investigations ...... 3 Field Investigation ...... 3 Laboratory Investigation ...... 4 4.2.1 Geotechnical Testing ...... 4 4.2.2 Corrosion Testing ...... 4 5 Subsurface Conditions ...... 5 Site Geology ...... 5 Summary of Subsurface Materials ...... 6 5.2.1 Fill (CL, GC-GM) ...... 6 5.2.2 Alluvium (CL-ML, SM, SC-SM, GM, GC-GM, GW, GP-GM) ...... 6 5.2.3 Residuum ...... 7 5.2.4 Bedrock ...... 7 5.2.5 Groundwater ...... 7 Geologic Hazards ...... 8 6 Design Recommendations ...... 9 General ...... 9 Shallow Foundations ...... 9 Deep Foundations...... 10 Lateral Earth Pressures ...... 11 Geotechnical Parameters for Counteracting Buoyancy ...... 12 Frost Heave ...... 13 Surface Drainage ...... 13 Site Piping ...... 13 6.8.1 Modulus of Soil Reaction (E’) ...... 14 6.8.2 Thrust Restraint ...... 14 Seismic Parameters ...... 14 ...... 15 7 Construction Procedures and Recommendations ...... 15 General ...... 15 Excavation Slopes ...... 16

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page ii of ii 7.2.1 Temporary Slopes ...... 16 7.2.2 Permanent Slopes ...... 17 Site Grading and Earthwork ...... 17 7.3.1 Site Preparation ...... 17 7.3.2 Excavations ...... 17 7.3.3 Engineered Fill Placement and Compaction ...... 18 7.3.4 Trench Backfill, Placement and Compaction ...... 19 7.3.5 Recommended Compaction Specifications ...... 20 Construction Dewatering ...... 20 Bedrock Excavation ...... 21 Micropile Construction ...... 21 8 Limitations ...... 21

TABLES

Table No. Title

I Summary of Geotechnical Laboratory Test Results II Summary of Corrosion Test Results

FIGURES

Figure No. Title

1 Site Vicinity 2 Boring Locations

APPENDIX A – Test Boring Key and Test Boring Reports APPENDIX B – Laboratory Testing Results

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 1 of 22

1 INTRODUCTION

Brierley Associates (Brierley) has been retained by Carollo Engineers, Inc. (Carollo) to conduct a geotechnical engineering investigation for proposed Nutrient Upgrades Project at the Avon Wastewater Treatment Facility (WWTF) located in Avon, Colorado. The purpose of the geotechnical investigation is to provide key subsurface and geotechnical information necessary to complete the foundation design and provide earthwork recommendations for the proposed structures and pavements.

In preparing this report, our firm has relied on the following references:

• 2015 International Building Code, Section 1613;

• American Society of Civil Engineers (ASCE), 2010, Minimum Design Loads for Buildings and Other Structures;

• Chen & Associates, 1984, Soil and Foundation Investigation, Proposed Building Addition, Avon Wastewater Treatment Plant, Avon, Colorado, dated June 5;

• Colorado Association of Geotechnical Engineers (CAGE), December 1996, Guidelines for Slab Performance Risk Evaluation and Residential Basement Floor System Recommendations’;

• Colorado Geological Survey (CGS), 2008, EG-14 Collapsible Soils in Colorado;

• Ductile Iron Pipe Research Association (DIPRA), 2017, Corrosion Control Polyethylene Encasement, revised January;

• HP Geotech, 2009, Geotechnical Engineering Study, Proposed Heat Recovery System, WWTP to West Benchmark Road, Avon, Colorado, dated September 30;

• Kosmatka, S.H., Beatrix Kerkhof, and William C. Panarese, Design and Control of Concrete Mixtures, Portland Cement Association (PCA), 14th Edition, 2002;

• Mock, R.G., and Pawlak, S.L., 1983, Alluvial fan hazards at Glenwood Springs;

• Mock R.G., 2015, Engineering Geologic Practices on the Western Slope;

• Occupational Safety & Health Administration, Standards 29 CFR, 1926 Subpart P App A;

• Peak Land Consultants (PLC), 2017, Topographic Map, Tract N and O, Benchmark at Beaver Creek, Town of Avon, Eagle County, Colorado, Sheet 1 of 3, dated February 1;

• Tweto, O., Moench, R.H., Reed, J.C., 1978, Geologic Map of the Leadville 1° x 2° Quadrangle, Northwestern Colorado, Scale 1:250,000.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 2 of 22 • United States Geological Survey (USGS), 2018, U.S. Seismic Design Maps Web Application, http://earthquake.usgs.gov/designmaps/us/application.php.

• USDOT, FHWA, 2005, Micropile Design and Construction Reference Manual, Publication No. FHWA-NHI-05-039, dated December;

• Other in-house geologic information and experience with similar projects.

2 SITE DESCRIPTION

The site for the proposed Nutrient Upgrades Project is on the western side of the existing Avon WWTF as shown in Figures 1 and 2. The site is bounded to the north by a parking lot followed by the DRGW Railroad, to the east by existing underground aeration basins and secondary clarifier building of the existing WWTF, to the south by a bike path followed by the Eagle River, and to the west by a multi-family residential development.

The site topography generally slopes southward toward the Eagle River, with elevations varying from approximately 7,410 feet above Mean Sea Level (MSL) to approximately 7,394 feet above MSL based on our review of the topography presented on the Topographic Map prepared by PLC (2017). Most of the site is currently developed with asphalt concrete pavement bordered by landscaping consisting of grass and trees and by the above- and below-grade aeration basin structures and the secondary clarifier building. Based on plans for the existing secondary clarifier building provided by Carollo, we understand the existing building is constructed atop a mat slab foundation with a bearing elevation of approximately 7,396’ in the elevation datum presented in PLC (2017). Plans for the underground aeration basin structures were not available for our review at the time of this report.

Brierley reviewed available aerial imagery of the site from Google Earth dating back to September 5, 1999 to develop an understanding of prior development activities which could potentially affect the subsurface conditions. The western portion of the existing WWTF has remained in a relatively similar condition since 1999, with no significant observable development occurring since then.

3 PROJECT DESCRIPTION

We understand the Nutrient Upgrades Project will consist of the design and construction of the following improvements:

• An addition to the existing aeration basin, which may or may not support a building. The addition will have a footprint of approximately 75 feet by 80 feet, an anticipated foundation bearing elevation of approximately 7,391 feet, and anticipated foundation loads of up to 4,000 pounds per square foot (psf) at the perimeter walls. Based on our review of the proposed bearing elevation and the existing topography, we anticipate the bottom of the proposed structure will be approximately 19 to 13 feet below ground surface (bgs).

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 3 of 22 • Secondary Clarifier 3, which will consist of a circular water-bearing basin that may or may not support a building. Secondary Clarifier 3 will have a basin with a 60-foot diameter and an overall structure footprint of 70 feet by 80 feet, with an anticipated foundation bearing elevation ranging between 7,381 feet 7,390 feet, and anticipated foundation loads of up to 4,000 pounds per square foot (psf) at the perimeter walls. Based on our review of the proposed bearing elevation and the existing topography, we anticipate the bottom of the proposed structure will be up to approximately 23 feet bgs.

• Various site paving and buried piping.

• Construction of a crane pad north of the proposed aeration basin addition to support the use of a crane during construction activities.

4 FIELD AND LABORATORY INVESTIGATIONS

Field Investigation

Brierley subcontracted Vine Laboratories, Inc. from Commerce City, Colorado to drill nine boreholes (BA-1 MW through BA-9). Borings BA-1 MW through BA-5 were drilled between August 6 and August 17, 2019. Borings BA-6 through BA-9 were drilled on February 1 and February 2, 2019. The boring locations were selected by Carollo and staked in the field by Brierley. The borings were conducted to investigate general subsurface conditions and to obtain samples to aid in the determination of engineering properties. The boring locations are depicted in Figure 2.

The borings were extended to depths ranging from 9.5 to 64.4 feet below the existing ground surface using 6-inch diameter solid stem augers and ODEX equipment with 4.25-inch O.D. casing. Modified California Barrel (2-inch I.D., 2-1/2-inch O.D.) and split spoon (1.5-inch I.D., 2- inch O.D.) samples were obtained in general accordance with Standard Penetration Test (SPT) procedures (ASTM D 1586). The penetration values reported in Section 5, General Subsurface Conditions, are the number of blows of a 40-lb hammer falling 30 inches, counted in 6-inch intervals. The Modified California Barrel and split spoon blow counts have not been converted to standard penetration N-values. Borings BA-1 MW and BA-4 MW were completed as temporary groundwater monitoring wells.

Descriptions and visual classifications of soil strata and samples were recorded on test boring reports during drilling. Soil descriptions follow the ASTM D 2487 or ASTM D 2488 Soil Classification System. Rock descriptions are in accordance with ASCE and ISRM descriptive systems for in-situ rock engineering properties. The completed test boring reports are provided in Appendix A along with an explanatory sheet defining the terms used on the reports. The subsurface conditions revealed by the field investigation are discussed in Section 5, Subsurface Conditions.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 4 of 22 Laboratory Investigation

4.2.1 Geotechnical Testing

To aid in classifying the soils and to determine general soil characteristics, selected laboratory tests were performed on representative samples. Test method references are shown in the following table:

Parameter Method Reference Moisture Content ASTM D 2216 Dry Density ASTM D 2937 -#200 Wash ASTM D 1140 Grain Size Distribution ASTM D 6913 Atterberg Limits ASTM D 4318 Unconfined Compressive Strength of Soil ASTM D 2166 Swell/Collapse ASTM D 4546 Sodium Adsorption Ratio USDA 60 6 (20b)

The test boring reports were amended as necessary to reflect laboratory test data. The results of the laboratory testing are summarized in Table I. Selected laboratory test results are included in Appendix B. Colorado Analytical Laboratory provided the sodium adsorption ratio laboratory analysis. The remainder of the geotechnical laboratory analysis was performed at Martinez Associates in Golden, Colorado.

4.2.2 Corrosion Testing

Bulk samples were obtained from the borings to determine the corrosive nature of soils. Tests included pH, chlorides, sulfides, sulfates, redox potential and resistivity (saturated); test method references are shown in the following table.

Parameter Method Reference Resistivity AASHTO T288-91 Sulfate AASHTO T290-91 / ASTM D 4327 pH AASHTO T289-91 Sulfide AWWA C105 Chloride AASHTO T291-91 / ASTM D4327 Redox Potential ASTM D 1498

The results of these tests are summarized in Table II. Colorado Analytical Laboratory provided the laboratory corrosion analysis. These results should be considered when evaluating corrosion potential of elements such as buried metallic piping and structures, driven steel piling, and concrete coatings and structures. Brierley has assumed that corrosion engineering will be performed by others.

We understand Carollo wishes to evaluate the corrosion testing results using the 10-point soil evaluation procedure created by DIPRA and presented in AWWA C105 Appendix A. For a given soil sample, various parameters are evaluated and assigned points according to its contribution to corrosivity, and if the sum is 10 or more, the soil is considered corrosive to Ductile Iron Pipe,

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 5 of 22 and DIPRA recommends protective measures should be taken. The AWWA C105 Appendix A scoring on each tested sample is presented in Table II.

5 SUBSURFACE CONDITIONS

A general description of the predominant stratigraphy encountered in the proposed areas of construction is presented below. For more detailed description of the subsurface conditions, please refer to the test boring reports provided in Appendix A. Figure 2 identifies the boring locations.

Site Geology

The site is in Avon, Colorado, within the Southern Rocky Mountains physiographic region of Colorado. The Laramide Orogeny uplifted the Rocky Mountains during the late Cretaceous and early Tertiary Periods and caused faulting and folding processes to occur. Additional regional uplift during mid-Tertiary time further uplifted the Rocky Mountains. Glaciers and rivers such as the Eagle River down-cut and excavated into the Rocky Mountains, forming mountain and valley topography, and exposing previously deposited strata near Avon. The mountain slopes near Avon generally expose sedimentary rocks deposited during the Cambrian to Cretaceous Periods.

Regional geologic mapping by Tweto et. Al (1978) indicates the site is in an area underlain by Pleistocene-age young gravels consisting of stream, terrace, and outwash gravels, presumably deposited by the Eagle River or derived from other streams north of the site. Bedrock of the Pennsylvanian-age Eagle Valley Formation and Eagle Valley Evaporite are mapped near the site. The Eagle Valley Formation is described as consisting of gray and reddish-gray siltstone, shale, sandstone, carbonate rocks, and local lenses of gypsum. The Eagle Valley Evaporite is described as consisting of gypsum, anhydrite, interbedded siltstone, and minor dolomite. Stratigraphically, the Eagle Valley Formation overlies the Eagle Valley Evaporite, but the contact between the two formations is known to be gradational and/or intertonguing in some areas.

Structurally, the site is located approximately 3.5 miles southwest of a mapped syncline fold axis, and geologic contact patterns near the site indicate that the site may be on the southwestern leg of the syncline. As such, it is possible that bedrock at the site is dipping toward the northeast, however the published geologic mapping does not indicate a dip angle or orientation near the site. Therefore, site excavations that extend into bedrock may expose various dipping strata at the excavation bottom.

Additionally, our subsurface exploration indicated that the top-of-bedrock surface generally sloped downward to the northwest near the proposed structures. As depicted in Figure 2 and shown in the boring logs, the subsurface exploration indicated top-of-bedrock elevations of approximately 7,391 feet in BA-4MW and elevations sloping downward to 7,368 feet in BA-7 and 7,355 feet in BA-6.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 6 of 22 Summary of Subsurface Materials

The following sections present a summary of the subsurface materials encountered during the subsurface exploration. More detailed information can be found on the boring logs in Appendix A and in Table 1, Summary of Laboratory Test Results.

5.2.1 Fill (CL, GC-GM)

Fill consisting of stiff to hard lean clay (CL) with sand and gravel, and medium dense to very dense silty, clayey gravel (GC-GM) with sand. The fill was encountered at the ground surface in Borings BA-5, BA-8, and BA-9, below asphalt pavement in Borings BA-4 MW and BA-7, below approximately 6 inches of topsoil in Boring BA-2, and below approximately 6 feet of pea gravel backfill in Boring BA-6, and extended to depths ranging from 6 to 14 feet bgs. The fill materials are likely a result of past grading associated with construction of the existing below-grade structures, utilities, and site driveways. Blow counts in the fill material ranged from 13 to 53 blows per foot (bpf). Laboratory testing performed on a sample of the fill material encountered in Boring BA-4 MW indicated a gravel content of 42.3 percent, and sand content of 37.1 percent, a fines content of 20.6 percent, a liquid limit of 44, and a plasticity index of 7.

5.2.2 Alluvium (CL-ML, SM, SC-SM, GM, GC-GM, GW, GP-GM)

The alluvium consisted of very stiff silty clay with sand (CL-ML); medium dense to very dense silty sand (SM), and silty, clayey sand (SC-SM), with varying sand content; and loose to very dense silty gravel (GM), silty, clayey gravel (GC-GM), well-graded gravel (GW), and poorly graded gravel with silt (GP-GM), with varying sand content. Boulders and cobbles were often noted during drilling through the alluvium, and sample recovery was often limited due to the presence of boulders and cobbles. The alluvium was encountered below approximately 5.5 inches of asphalt concrete in boring BA-1 MW, below the fill materials in Borings BA-2, BA-4 MW, BA-5, BA-6, BA-7, BA-8, and BA-9; and below approximately 4 inches of topsoil in Boring BA-3 and extended to depths ranging between 9.5 to 57 feet. Blowcounts in the alluvium ranged from 6 bpf to 50 blows without measurable penetration (50/0”). The moisture content and in-situ dry density of one sample were 2.1 percent and 112.9 percent, respectively. Eight sieve analysis tests were performed on the alluvium. The gravel contents ranged from 9.4 to 63.4 percent, the sand contents ranged from 27.3 to 63.1 percent, and the fines contents ranged from 7.3 to 27.5 percent. Six Atterberg limits tests were completed on the alluvium indicating liquid limit results of non-plastic and 21, and plasticity index results of non-plastic and 6. One swell/consolidation test performed on a sample of the alluvium from boring BA-1 collected at a depth of 8.2 to 9.2 feet bgs indicated a collapse of 7.8 percent when wetted at an applied pressure of 1,000 pounds per square foot (psf).

The alluvium encountered in structure footprint areas below an elevation of approximately 7,390 feet and above groundwater and/or bedrock generally contained few or little fines. Laboratory sieve analysis testing on the alluvium below an elevation of 7,390 feet indicated fines contents ranging from 7.3 to 13.8 percent.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 7 of 22 5.2.3 Residuum

Residuum, representing weathered bedrock material with relatively low blowcounts compared to the bedrock, was encountered below the alluvium in Boring BA-5 at a depth of approximately 9.3 feet and extended to the depth explored of 9.5 feet. The residuum consisted of very soft, highly weathered siltstone.

5.2.4 Bedrock

Bedrock consisted of very soft to hard, completely weathered to fresh, uncemented to strongly cemented, shale, sandstone, and siltstone consistent with the Eagle Valley Formation. The bedrock was encountered below the alluvium in borings BA-1 MW through BA-4 MW. Blow counts in the bedrock ranged from 64 bpf to 100 blows per 3 inches (100/3”).

Laboratory testing was performed on 2 specimens of the sandstone. The sandstone had fines contents of 26.8 and 27.8, liquid limits of 21 and 28, and plasticity indices of 5 and 6.

Laboratory testing was performed on 5 specimens of the shale. The shale had moisture contents ranging between 2.8 and 14.1 percent, dry densities ranging from 115.5 to 131.0 , liquid limits ranging between 24 and 29, and plasticity indices ranging between 8 and 11. Based on four unconfined compressive strength tests, the strengths ranged between 0.9 and 9.7 kips per square foot (ksf). Two swell-consolidation tests indicated a collapse of 0.2 to 1.6 percent when wetted at an applied load of 1,000 psf.

5.2.5 Groundwater

Groundwater was encountered while drilling Borings BA-1 MW, BA-4 MW, BA-6, BA-7, and BA- 8. Subsequent readings were obtained from the BA-8 borehole which was left open overnight after drilling and from the monitoring wells installed at BA-1MW and BA-4MW as shown in the table below. The monitoring wells consist of 2-inch diameter schedule 40 PVC pipe with caps at the bottom and top. Further well construction details are presented in the boring logs in Appendix A. In general, groundwater levels may rise to elevations higher than initially encountered due to the relatively slow rate of seepage in fine soils and fine-grained bedrock. Additionally, variations in the groundwater level may occur due to variations in the level of the nearby Eagle River, rainfall, temperature, site development, extraction or injection of groundwater, and other factors not evident at the time that these measurements were made. The subject site is in an area shown by FEMA as having a cross section line with a 1 percent annual chance of flooding at an elevation of 7,392.4 feet.

Groundwater Readings

(depth below ground surface in feet) Boring During Drilling 8/17/18 2/1/19 2/2/19 BA-1 MW 29.5 29.3 30.2 - BA-4 MW 22.0 22.3 - 25.2 BA-6 35.2 BA-7 32.6 BA-8 30.0 29.3

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 8 of 22 Geologic Hazards

The following discusses potential geologic hazards at the site including faulting and seismicity, liquefaction potential, expansive soils, and compressible/collapsible soils.

Historically, several minor earthquakes have been recorded in the Eagle County area. Based on our field observations and our review of readily available published geological maps and literature there are no known active faults underlying or adjacent to the subject site. Therefore, the probability of damage at the site from seismically induced ground surface rupture from faults is low.

Design of the proposed improvements should be performed in accordance with the requirements of the applicable building codes. Section 6.3 presents the seismic design parameters for the site in accordance with the 2015 International Building Code guidelines using the web-based USGS ground motion calculator (USGS, 2018).

Loose saturated granular soils of low plasticity; and non-plastic silts within 50 feet of the surface and below the water table can be susceptible to liquefaction during cyclic loading such as exhibited during seismic events. However, given the relatively dense soils encountered below the proposed building envelopes and the relatively low ground accelerations anticipated during a seismic event at the site, we do not regard liquefaction as a potential hazard for the site.

Moisture changes to bedrock or surficial deposits containing swelling clays can result in volumetric expansion and collapse of those units. Changes in soil moisture content can result from rainfall, irrigation, pipeline leakage, surface drainage, perched groundwater, drought, or other factors. Volumetric change of expansive soil may cause excessive cracking and heaving of structures with shallow foundations, concrete slabs-on-grade, or pavements supported on these materials. Based on one swell-consolidation test performed on the alluvium, the swell potential was low as defined by CAGE (1996). Based on two swell-consolidation tests performed on the shale bedrock, the swell potential was low as defined by CAGE (1996). Based on the findings of the subsurface investigation and the laboratory test results, we do not regard swelling soils or rock to be a design consideration for the proposed project.

Soil collapse (or hydro-collapse) is a phenomenon where soils undergo a significant decrease in volume upon an increase in moisture content, with or without an increase in external loads. Structures and other improvements may be subject to excessive settlement-related distress when compressible soils or collapsible soils are present. In the Eagle River Valley, there are many known occurrences of collapsible-soils, particularly in certain gypsiferous colluvial and alluvial sediments derived from evaporite-bearing rock formations including the Eagle Valley Evaporite, and the Eagle Valley Formation (CGS, 2008). Our review of published geologic mapping in the vicinity of the site indicates it is possible that portions of the on-site alluvial soils have been derived from such evaporite-bearing rock formations.

One swell-consolidation test performed on the alluvium in Boring BA-1MW at a depth of 8.2 to 9.2 feet bgs (corresponding to an approximate elevation of 7,399.8 to 7,398.8 feet) with 27.5 percent silty, clayey fines indicated a collapse of 7.8 percent when wetted under an applied pressure of 1,000 psf, corresponding to a high collapse potential as defined by Mock & Pawlak (1983). However, the alluvium encountered in structure footprint areas below an elevation of approximately 7,390 feet and above groundwater and/or bedrock generally contained few or

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 9 of 22 little fines. Laboratory sieve analysis testing performed on the alluvium below an elevation of 7,390 feet indicated fines contents ranging from 7.3 to 13.8 percent. Due to the generally gravelly nature of the alluvial soils encountered below the proposed structure foundations, we were unable to obtain undisturbed samples suitable for laboratory collapse testing at these depths. However, based on the relatively low fines content of the alluvial soils encountered beneath the proposed foundation elevations, it is our opinion that the risk of hydro-collapse is relatively low for these soils. Based on our background review, subsurface investigation, laboratory testing, and our understanding of the proposed structures, we recommend supporting the foundations and slabs for the aeriation basin addition and the Secondary Clarifier 3 on a zone of moisture conditioned and engineered fill material extending to bedrock or groundwater, or to a depth of three feet below the bottom of the proposed foundation as discussed in Section 6.2.

Sinkholes and subsidence are also known to occur in the region as a result of dissolution of evaporitic bedrock, particularly in association with gypsum and anhydrite strata within the Eagle Valley Evaporite (Mock, 2015). Based on the predominantly shale bedrock encountered in the subsurface exploration within the footprint of the proposed aeration basin addition and the Secondary Clarifier 3, we do not regard subsidence from dissolution of evaporitic bedrock to be a design consideration for the proposed project. However, as noted in Section 5.1, the contact between the Eagle Valley Formation and the Eagle Valley Evaporite is known to be intertonguing in some areas and it is possible that bedrock at the site is dipping toward the northeast. Therefore, site excavations that extend into bedrock may expose various dipping strata at the excavation bottom, potentially including dipping dissolution-prone bedrock. As such, we recommend field observations of the open foundation excavations should be performed by a representative of the geotechnical engineer prior to backfilling with engineered fill material to confirm the absence of dissolution-prone bedrock and/or to make corrective recommendations as necessary.

6 DESIGN RECOMMENDATIONS

General

The recommendations for design and construction presented in the following sections are based on Brierley’s understanding of the proposed construction, an engineering assessment of the anticipated subsurface conditions, and Brierley’s experience with similar projects in similar soil conditions. If there are any changes in these project criteria, a review should be made by this office prior to final design and construction at the site.

Shallow Foundations

Based on our understanding of the ground surface elevations, the findings of our subsurface exploration, and the proposed structure elevations, the Secondary Clarifier 3 structure is generally planned at a depth partially within the bedrock and partially within the alluvium, and the aeration basin addition is generally planned at a depth within the alluvium. Based on the relatively low fines content of the alluvial soils encountered beneath the proposed foundation elevations, it is our opinion that the risk of hydro-collapse is relatively low for these soils. To mitigate the low risk of hydro-collapse for the soils below the proposed structures, we recommend that the alluvium be overexcavated to a depth of three feet below the bottom of the

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 10 of 22 proposed foundations. This recommendation can be reconsidered if groundwater or bedrock are encountered within the 3 foot depth. The overexcavation should be backfilled with moisture- conditioned and compacted engineered fill as discussed in Section 7.3.3.

The structure may be founded on conventional spread footings or a mat foundation bearing on the reconditioned soil. A net allowable bearing pressure of 3,500 psf should be used for the design of the shallow foundations.

The allowable bearing pressures may be increased by 33 percent for short term or infrequent loading such as wind and seismic loads. In using net pressure, the weight of the soil column above the portion of the footing that protrudes beyond the foundation wall need not be considered. The recommended minimum dimension of continuous or isolated footings is 18 inches.

Resistance of foundations against sliding will depend on the bearing material. A coefficient of frictional resistance of 0.45 may be used. The recommended modulus of subgrade reaction for the subgrade soils is 250 psi/inch.

Field observations of the open foundation excavations should be performed by a representative of the geotechnical engineer prior to backfilling with engineered fill material to confirm the absence of dissolution-prone bedrock and/or to make corrective recommendations as necessary.

Additionally, field observations and testing of the prepared footing and slab subgrade should be performed by a representative of the geotechnical engineer prior to concrete placement to verify that the subgrade is suitable for foundation placement or to make mitigative recommendations as appropriate.

For footings designed as recommended above and bearing on subgrade soils prepared in accordance with our recommendations in Section 6, total and differential settlements are estimated to be less than approximately 1-inch and ½-inch over a horizontal span of 40 feet, respectively.

Deep Foundations

We understand the proposed project will include construction of a crane pad north of the proposed aeration basin addition to support the use of a crane during construction activities. Due to the anticipated crane loads, we recommend the proposed crane pad be supported on foundations which extend into very dense alluvium and/or shale bedrock.

We anticipate construction of drilled shaft-type foundations will not be feasible due to the presence of boulders and cobbles in the alluvium and difficult auger drilling conditions. We anticipate micropile-type foundations will be feasible to construct at the proposed crane pad location if mud rotary or similar drilling methods are used to advance the micropile boring through the alluvium and into bedrock (if needed).

During the subsurface investigation, we encountered shale of the Eagle Valley Formation at a depth of 57 feet bgs in Boring BA-6 near the proposed crane pad. Laboratory testing performed on the shale at the site did not indicate swell potential. The shale encountered was below the

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 11 of 22 groundwater level encountered during drilling. The overburden materials generally consisted of coarse alluvium and fill with a low fines content and low plasticity. As such, we anticipate the design of micropile foundations may neglect uplift pressures due to swelling soil and bedrock. However, micropile excavations should be observed by a representative of the geotechnical engineer during construction to confirm the ground conditions are consistent with the ground conditions encountered during the subsurface investigation.

Recommendations for the design of micropile-type foundations (micropiles) bottomed in the shale bedrock are presented in the following sections:

A. Due to the presence of groundwater, micropiles should be designed and installed in accordance with Case I, Type B1 requirements as specified in U.S.D.O.T. publication number FHWA-NHI-05-039.

B. Drilling methods shall be determined by the contractor. Drilling methods shall be capable of advancing through hard granitic boulders in the alluvium.

C. Micropiles should be designed using ultimate grout to ground interface bond strength of 30 psi in shale bedrock, and 10 psi in the alluvium. Grout to ground strength should be neglected for the upper 15 feet below ground surface. Assuming pre-production testing and production pile proof testing is performed, a factor of safety of 2 should be used. End bearing pressure should ignored for micropile design.

D. Micropiles should be spaced to balance loads. At a minimum, micropiles should have a center-to-center spacing of at least 3 micropile diameters to avoid group efficiency effects. Brierley should be contacted if any micropiles will be spaced closer than 3 diameters.

E. Brierley estimates that foundation settlements should not exceed approximately one inch.

F. Pre-production testing and production pile proof testing should be performed on as discussed in Section 7.6.

Lateral Earth Pressures

Lateral pressures will be exerted on below grade walls by backfill soils, surcharge loads, and hydrostatic pressures caused by groundwater. Lateral earth pressures on walls depend upon the type of wall, type of backfill material and allowable wall movements. For walls that are restrained at the top, lateral earth pressures should be estimated for an “at rest” condition. For walls that are free to deflect at the top, the “active” condition may be used. We recommend that the active condition may be used for the wall design if the below grade walls have calculated deflections of at least 1 percent of the wall height. We recommend that the structure walls and any potential foundation walls be backfilled with Engineered Fill in accordance with the recommendations presented in Section 7. The recommended lateral earth pressures are provided in the tables below:

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 12 of 22

Lateral Earth Pressures -- Static Coefficient of Lateral Equivalent Fluid Pressure (pcf) Earth Pressure Unit Friction Active At-Rest Passive Wt. Angle At- Above Below Above Below Above Below Active Passive (pcf) (deg) Backfill Rest GW GW GW GW GW GW Engineered 42 83 63 94 375 250 0.33 0.50 3.00 125 30 Fill

Additional Lateral Earth Pressures due to Seismic Loading Seismic Coefficient of Point of Equivalent Fluid Pressure (pcf) Lateral Earth Pressure Application Active At-Rest Passive of At- Above Below Above Below Above Below Active Passive Additional Backfill Rest GW GW GW GW GW GW Loading 0.6H up Engineered from the 8 4 12 5 -20 -11 0.06 0.10 -0.16 Fill base of the wall Notes: 1) Assumed properties for on-site residuum and fill soils. 2) Seismic lateral Earth pressures based on peak ground acceleration. 3) Based on Mononobe-Okabe model and Das, 1983. 4) GW = Groundwater. 5) The above values assume that top of backfill surface is level ground rather than sloping ground.

The recommended equivalent fluid pressures for foundation conditions below the water table include hydrostatic pressure. For designing below grade walls, we recommend a design groundwater elevation of 7,392 feet, corresponding to a major flood event on the Eagle River. Care must be taken when including passive pressures in design because the ground movement required to mobilize passive pressure is greater than that needed to create active or at-rest conditions; approximately half of the passive pressure can be utilized if a deflection of 0.5% of the wall height can be tolerated.

Geotechnical Parameters for Counteracting Buoyancy

The proposed structures should be evaluated for buoyancy using a design groundwater elevation of 7,392 feet, corresponding to a major flooding event on the Eagle River. Where the structure loads are not sufficient to counteract buoyancy, additional resistance to uplift can be achieved by extending the foundation outside the vertical walls and engaging the weight of an additional wedge of soil. For design purposes, the wedge of soil providing resistance on the extended foundation can be defined by including the soil within a 12-degree slope (measured from vertical) up and away from the bottom exterior edge of the extended footing to the ground surface.

A saturated unit weight of 125 pcf may be used for the soil wedge if the buoyant force on the structure includes the weight of water displaced by the soil wedge. If the buoyant force on the

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 13 of 22 structure does not include the weight of water displaced by the soil wedge, i.e. only the volume of water that is displaced by the structure itself, then a soil unit weight of 60 pcf should be used.

Frost Heave

Exterior wall footings and footings in unheated areas should be located at a depth of at least 36 inches below final exterior grade for frost protection.

Surface Drainage

Construction details should ensure that surface water does not penetrate the backfill or utility trenches and migrate beneath the structures. Any planned landscaping, pavements, sidewalks and parking areas should be sloped away from the structures to prevent ponding of water. A minimum slope of 6 inches in the first 10 feet from the building is recommended. Roof downspouts should extend a minimum of 5 feet beyond the limits of the foundation backfill. Plants should not be located within 5 feet from the building. Irrigation systems should be arranged so that water under full pressure does not spray within 5 feet of foundation walls. If lawn edging is used around the exterior of the building, it should be perforated to prevent ponding of surface water near the backfill soils. The exterior backfill should not be covered with a polyethylene moisture barrier. Instead, a weed suppressant geotextile fabric, such as Mirafi 140S or equivalent, may be used to allow for natural evaporation of the backfill soils.

Site Piping

Piping plans for the project were not provided for review at the time of this report. As such, it is anticipated the piping will potentially be installed within the fill materials, the alluvium, the residuum, and the bedrock. All piping within and near the structure footprints should be embedded in and backfilled with cementitious flowable fill to help minimize the risk of water collecting in permeable materials and potentially causing hydrocollapse within the alluvial materials. Piping that is located at least 10 ft away from building perimeters may be embedded in a clean granular material from a depth of 6 inches below the pipe to 6 inches above the pipe. Bedding can consist of ASTM C33 No. 7 coarse aggregate with less than 5 percent fines or well-graded sand with a maximum size of 3/8-inch as shown below.

Sieve Size Percentage Passing 3/8-inch 100 #4 70-100 #8 36-93 #16 20-80 #30 8-65 #50 2-30 #100 1-10 #200 0-3

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 14 of 22 6.8.1 Modulus of Soil Reaction (E’)

The modulus of soil reaction (E’) is an empirically derived coefficient which is related to the stiffness of the native soils and the nature and degree of compaction of the pipe bedding and backfill material. Various design guidelines specific to pipe material provide recommended values for E’. For full embedment in compacted granular pipe bedding an E’ value of 1,500 psi should be used for PVC and steel pipe and 700 psi for ductile iron pipe.

This E’ value is applicable when the trench is excavated in soils that are loose/medium stiff or better (stiffer or denser), typically with blow counts greater than 4 blows per foot, and where the trench width measured at the pipe elevation (Bd) is at least 2 times the pipe diameter (D).

6.8.2 Thrust Restraint

Thrust restraint for pipelines may be provided using restrained joints or thrust blocks. Thrust blocks bearing against native soils and used to encase tee connections and bends may be designed using a passive earth pressure. Passive earth pressure can be assumed to be fully mobilized when movement equals 0.02 times the height of the thrust block. However, passive earth pressures less than the fully mobilized value are generated with significantly less movement. Assuming a negligible amount of movement, a passive earth pressure of 300 pcf per foot of depth with an average pressure over the face of the thrust block not to exceed 1,750 psf may be used.

A coefficient of friction (μ), between the steel pipe and granular pipe zone bedding material, of 0.10 may be used for both saturated and unsaturated conditions. For designing restrained joints using the Ductile Iron Pipe Research Association (DIPRA) method, the backfill can be classified as clean sand with a friction angle of 34 degrees.

Seismic Parameters

Brierley has reviewed ASCE 7-10 and the 2015 International Building Code, with respect to geotechnically related seismic design parameters. Based on this review, the soil is classified as Site Class C (Very dense soil and soft rock).

Seismic design parameters for the structures were obtained using the 2008 United States Geological Survey Geologic Hazards Center and US Seismic Design maps. The Seismic Design Parameters software utilizes the same maps and parameters as the IBC 2015 while allowing for parameter calculations for specific site classes. The input parameters consisted of ASCE 7-10 Standard, and Site Class C, Risk Category III, and the latitude and longitude. The parameters apply to the proposed structure and are presented in the following table.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 15 of 22

PGA Ss SMS SM1 SDS SD1 TL S1 PGAM Fa Fv (g) (g) (g) (g) (g) (sec) (g) (g)

0.148 0.268 0.322 0.127 0.214 0.084 4 0.074 0.178 1.2 1.7

Based on the values provided in the table above and experience with the local and regional potential for seismic events, it is Brierley Associate’s opinion that the risk at the site is low for the occurrence of earthquake-induced geologic hazards such as ground surface rupture, settlement, liquefaction, or lurching.

Pavement Design Recommendations

On-site pavement for access roads and parking areas should consist of 6 inches of full-depth asphalt (without base course) or 4 inches of asphalt over 8 inches of Class 6 base course. In high traffic areas and where trucks make tight turns 6 inches of concrete without base course should be used. The pavement sections should be constructed atop a minimum 1-foot thick zone of moisture conditioned and compacted Engineered Fill. The resulting subgrade should be proofrolled to verify stability and if the proofroll reveals soft or loose soils, the subgrade should be stabilized. Stabilization can be accomplished using geotextile stabilization or by utilizing rockfill material over the base of the excavation.

7 CONSTRUCTION PROCEDURES AND RECOMMENDATIONS

General

Variations in soil conditions will be encountered during construction. To correlate design concepts with actual soil conditions encountered during construction, Brierley recommends that technical or engineering personnel be present to provide monitoring and geotechnical engineering services during construction and to assist in developing design changes if subsurface conditions differ from those outlined in this report. A geotechnical engineer should observe initial excavation conditions to determine whether encountered conditions are like those anticipated. Brierley can be retained to provide this service.

The following sections of this report include comments on items related to excavation, dewatering, foundation construction, earthwork, and related geotechnical engineering aspects of the proposed construction. This section is written primarily for the engineer responsible for the preparation of plans and specifications. This section also addresses construction issues related to foundations and earthwork and will aid personnel who monitor construction activity.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 16 of 22 The Contractor must evaluate potential construction problems based on their own knowledge and experience and based on similar projects in other localities, considering their own proposed construction methods and procedures.

Excavation Slopes

7.2.1 Temporary Slopes

The Contractors should make themselves aware of and become familiar with applicable local, state, and federal safety regulations, including the current OSHA Excavation and Trench Safety Standards. Construction site safety is the sole responsibility of the Contractor who shall also be solely responsible for the means, methods, and sequencing of construction operations. Brierley is providing this information solely as a service to our client. Under no circumstances should the information provided below be interpreted to mean that Brierley is assuming responsibility for construction site safety or the Contractor’s activities; such responsibility is not being implied and should not be inferred.

The Contractor should be aware that slope height, slope inclination, or excavation depths should in no case exceed those specified in local, state, or federal safety regulations (e.g., OSHA Health and Safety Standards for Excavations, 29 CFR Part 1926, or successor regulations). Such regulations are strictly enforced and, if they are not followed the Contractor and its subcontractors could be liable for substantial penalties.

Subsurface conditions will consist of fill, alluvium, residuum, and bedrock. Moderately weathered to fresh bedrock may be classified as Type A material. The fill, alluvium, residuum, and completely to highly weathered bedrock are generally sandy and gravelly and are considered Type C material when applying the OSHA regulations. OSHA recommends a maximum slope incline of 0.75:1 (horizontal: vertical) for Type A material and 1.5:1 for Type C material.

The soils to be penetrated by the proposed excavations may vary significantly across the proposed construction. Brierley’s preliminary soil classification is based solely on the materials encountered in nine borings. The Contractor should continually classify the soils that are encountered as trench excavation progresses with respect to the OSHA system.

As an alternative to temporary slopes, vertical excavations can be temporarily shored. We anticipate the use of shoring may be desired for the proposed excavations due to the proximity to property lines, utilities, and adjacent structures. The Contractor or the Contractor’s specialty subcontractor should be made responsible in the specifications for the design of the temporary shoring in accordance with applicable regulatory requirements.

Limiting the time that trench excavations remain open reduces the potential for unstable conditions to develop that can lead to raveling, sloughing, or failure of the trench walls. Slough from trench walls also accumulates on the trench floor requiring additional cleaning of the trench prior to pipe installation.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 17 of 22 7.2.2 Permanent Slopes

Brierley recommends a maximum slope of 3:1 for permanent cut and fill slopes, if planned. Erosion control may be required for slope stabilization. There are several options regarding erosion control including temporary erosion control blankets in conjunction with establishment of permanent vegetation, as well as other measures.

Site Grading and Earthwork

7.3.1 Site Preparation

After rough grade has been established for at-grade improvements such as pavements, flatwork, and utilities, the exposed subgrade should be carefully inspected by probing and testing as needed. Any topsoil or other organic materials still in place, frozen, wet, soft or loose soil, and other undesirable materials, as determined by the geotechnical engineer, should be removed. Areas where stable soils are encountered at subgrade levels should be scarified and compacted as outlined in this report under Recommended Compaction Specifications, prior to backfill placement. The exposed materials should be scarified to a minimum depth of 12 inches and moistened or dried if necessary, then recompacted as discussed in Section 7.3.3 and 7.3.5.

Fill material placed directly on existing slopes or proposed cut slopes has an increased risk of sliding failure at the contact between new and existing material. Therefore, slopes to receive fill, including potential excavation slopes behind the proposed structure walls, should be benched prior to fill placement.

Care should be exercised during the trenching operations at the site. The excavations should be performed during a dry season, if possible. The Contractor should account for potential shrinkage and bulking which are defined as the change in volume of the soil from its in-situ condition following excavation, moisture conditioning, placement, and compaction. The Contractor will need to provide separation and/or processing of the excavated soils for reuse purposes. We estimate that the excavated soil will bulk approximately 15 percent from in-situ to stockpile and will shrink 25 percent from stockpile to compacted fill.

7.3.2 Excavations

Overexcavation for the proposed structure slabs and foundations should extend to a depth of 3 feet below the bottom of the proposed foundations or to groundwater, whichever is less. Additionally, in areas where the proposed foundations are within or near bedrock, we recommend a at least 1-foot of overexcavation below the bottom of the proposed footings and slabs to allow for a minimum 1-foot thick zone of moisture conditioned and compacted Engineered Fill. The overexcavations should extend laterally beneath the entire structure footprint and outside the footprint for a minimum distance of 5 feet where possible.

Based on our understanding of the proposed structure foundation elevations and the subsurface exploration findings, we preliminarily anticipate the excavations for the Secondary Clarifier 3 structure will be up to approximately 24 feet deep and extend up to approximately 11 feet into bedrock to meet our recommended overexcavation criteria. We preliminarily anticipate the excavations for the aeration basin addition will be up to approximately 20 to 29 feet deep to meet our recommended overexcavation criteria. We anticipate portions of the aeration basin

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 18 of 22 excavation will extend to the top of bedrock, and portions of the excavation may terminate in the alluvium above groundwater.

Overexcavations in the structure footprint areas should be observed by a representative of the geotechnical engineer to confirm an adequate depth is achieved, to confirm the absence of dissolution-prone bedrock, and to verify that any existing uncontrolled man-made fill, loose, soft or otherwise undesirable materials are removed. The Contractor is responsible to determine and provide the equipment necessary for open trench excavation.

Soils exposed in the bottoms of the structure footprint overexcavations should be compacted to the specifications outlined and should also be protected against any detrimental change in conditions such as from disturbance, rain and freezing. Surface run-off water should be drained away from the excavation and not allowed to pond. If soft/loose pockets or undesirable materials are encountered in the bottoms of the excavations, the proposed excavations may be re-established by backfilling with engineered fill after the material has been removed. If the base of the overexcavation is still soft and further overexcavation is not practical, then a woven geotextile such as Mirafi 600x should be placed prior to backfilling. The backfill should be placed and compacted according to specifications outlined in this report.

Excavations should not undermine existing foundations and should not extend below a plane that extends downward and outward from the bottom outside edge of existing foundations on a 1:1 (horizontal:vertical) slope. Alternatively, the soils beneath the foundations of the existing structures should be appropriately shored during grading and excavation activities. The geotechnical consultant should be retained to observe the exposed soils during excavations along the base of existing footings to assess the suitability and stability of the exposed soil.

7.3.3 Engineered Fill Placement and Compaction

The proposed footings, slabs, and pavements should be supported on Engineered Fill. Structure walls should be backfilled with Engineered Fill. The Engineered Fill material should contain 10 to 50 percent gravel, 20 to 70 percent sand, and 10 to 40 percent fines, have a PI less than 20, and have low swell potential. The fill composition should be confirmed prior to use. The material should have a maximum particle/clod size of 3 inches. Bedrock fragments may be incorporated into the material if processed into a particle size of 3 inches or less. On-site soils may be used as Engineered Fill if processed to ensure a relatively uniform gradation and meet the requirements in this section.

Fill placed under structure foundations and backfill used next to walls and pipes should be placed in maximum 8-inch loose lifts and compacted. Only lightweight compaction equipment (hand held or walk behind) should be operated directly above pipes and adjacent to foundations.

Field density tests should be performed on each lift as necessary to verify that adequate compaction is being achieved. Mechanical compaction is required for all types of pipe bedding and for trench and structure fill and backfill. Compaction of any material by flooding or any method involving large quantities of water is not considered acceptable. This method will generally not achieve the desired compaction and the large quantities of water will tend to soften and/or cause swelling of the subgrade soils.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 19 of 22 In addition to field density testing, foundation subgrade and structure slab subgrade should be observed by a representative of the geotechnical engineer to verify the footings and slab will bear on firm subgrade. At the time of such observation, it may be necessary to make hand auger borings and/or use a hand penetration device in the base of the foundation excavation to confirm that the soils below the base are satisfactory for foundation support. The necessary depth of penetration will be established during observation.

Footing and slab subgrade should also be protected against any detrimental change in conditions such as from disturbance, rain and freezing. Surface run-off water should be drained away from footing excavations and not allowed to pond. Field observations and testing of the prepared footing and slab subgrade should be performed prior to concrete placement to verify the subgrade conditions and/or to make corrective recommendations as necessary.

7.3.4 Trench Backfill, Placement and Compaction

Backfill should be placed in lifts and compacted according to the specifications outlined in this report, Recommended Compaction Specifications. Backfill material should be placed in uniform horizontal layers which may not exceed 6 inches compacted depth in all areas. Only lightweight compaction equipment should be operated within 2 feet above the top of the pipe or adjacent to the pipe. Field density tests should be performed on each lift as necessary to verify that the specified compaction is being achieved.

Piping that is located at least 10 ft away from the building perimeter may be embedded in a clean granular material from a depth of 6 inches below the pipe to 6 inches above the pipe. All piping within and near the structure footprint should be embedded in and backfilled with low- strength cementitious flowable fill. In lieu of the flowable fill, clayey backfill may be used for backfilling flexible pipe joints if flowable fill is deemed too rigid. Above the pipe bedding, onsite materials may be used for trench backfill. Excavated bedrock should not be used for trench backfill material. Material greater than 3 inches measured in least dimension should not be placed within 1 ft of the pipe and material greater than 6 inches measured in least dimension should not be placed in the trench.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 20 of 22

7.3.5 Recommended Compaction Specifications

Material Not Exhibiting a Well- Material Exhibiting a Well-Defined Defined Moisture-Density Relationship Moisture- Density Fill Type Relationship Moisture Content Relative Minimum Minimum % of to Optimum Moisture Relative Standard Proctor Content Density (ASTM D 698) (ASTM D Maximum Dry Granular Cohesive Soils 4253 and D Density Soils 4254) Engineered Fill beneath slabs/ 98% -1 to +3% -2 to +2% foundations Engineered Fill not beneath 95% -1 to +3% -2 to +2% slabs/ foundations Recompacted native soils above and 95% -1 to +3% -2 to +2% beneath pipe zone

Pipe zone NA NA -2 to +2% 65%

Construction Dewatering

Groundwater levels measured during drilling in BA-6, BA-7, and BA-8 and in monitoring wells BA-1 MW and BA-4 MW within the structure footprints indicate groundwater elevations varied between 7,376.4 and 7,381.7 feet. Based on our understanding of the proposed project and the anticipated excavation depths, we anticipate construction dewatering will be required.

The elevation of the groundwater table varies seasonally. If excavation is performed during the wet season, the elevation of the groundwater may be substantially higher and be encountered in other areas. Several temporary dewatering wells or numerous vacuum well points may be required to draw the water table down. Trench drains, deep wells and well points are the most common dewatering methods. Construction dewatering will likely require closely spaced deep wells and/or well points and large volumes of pumped water.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 21 of 22

Bedrock Excavation

We anticipate the construction proposed structures will require excavation into shale, sandstone, and siltstone. We anticipate bedrock excavation can be performed with large excavators equipped with a ripper tooth. If processed into particle sizes of 3 inches or less, the bedrock may be incorporated into the Engineered Fill. Excavated material could also potentially be used as but not limited to riprap, slope reinforcement, or erosion control.

Micropile Construction

An experienced and competent contractor should be retained to install the micropiles. The contractor should have a track record of five or more years of experience in design and construction of micropiles. A qualified representative of the contractor should be involved during micropile installation to provide quality control. The locations and angle of installation should be clearly shown on the plans for all micropiles. Final design of the micropile foundation systems including size, spacing, and bedrock penetration should be based on available data and the results of pre-production testing and production pile proof testing.

Verification load testing should be performed on one or more pre-production test piles near locations where the micropiles are planned. Load testing should be performed prior to installation of the production piles. The test piles may be used as production piles provided the piles are designed with a structural factor of safety of 1.25 or more at the maximum test load, the piles have not failed or been overloaded during testing, and the pile can be replaced if the pile fails. A representative of the geotechnical engineer should be present during pre-production pile load testing to observe and document testing conditions and results. Based on the findings of the load tests, design axial capacities may be reevaluated for planned production piles.

Installation of micropiles should be observed by a representative of the geotechnical engineer to confirm the depth, vertical alignment, the bearing strata, reinforcing steel placement, and grout placement. Grout used in piles should be sampled and tested for strength.

Proof testing should be performed on production piles. The frequency of proof testing should be implemented based on the experience of the contractor. Preliminarily, a minimum of 5 percent of the number of production piles should be planned for proof testing. Based on the results of the initial proof testing, additional testing may be recommended. The proof testing should be monitored in the field by a representative of the geotechnical engineer. The design engineer should evaluate the need for additional micropiles based on the results of the proof testing program.

8 LIMITATIONS

This report has been prepared for specific application to the Avon WWTF Nutrient Upgrades Project per agreement between Brierley Associates and Carollo Engineers. This report was based on our understanding of the project elements and geometry at this time and in accordance with generally accepted engineering practices common to the local area.

Geotechnical Engineering Report Avon Wastewater Treatment Facility 3/27/2019 Page 22 of 22

If changes in the nature, design, or location of the planned construction are made, the conclusions and recommendations contained in this report should not be considered valid, unless the changes are reviewed by Brierley and the conclusions of this report are modified or verified in writing.

Discussions of soil and groundwater conditions described herein are based on subsurface information obtained from widely spaced test borings. Hence, prospective Contractors for this project should expect variation in physical properties for the various geologic strata encountered. Boundaries between soil types presented our test boring reports are approximate and transitions between material types may be gradual.

Subsurface conditions, especially degree of weathering, soil and bedrock consistencies and groundwater levels may change with time.

The scope of Brierley Associates services does not include an environmental assessment and do not provide an evaluation of the presence or absence of hazardous or toxic materials in the soil, bedrock, groundwater, or surface water within or beyond the project boundaries. Any statements in this report or on the test boring reports regarding odors or other unusual conditions observed are strictly for the information of our client. If not already conducted, we recommend an environmental assessment of the site be conducted by a qualified professional prior to initiation of any excavation and/or construction at the site.

TABLE I SUMMARY OF GEOTECHNCIAL LABORATORY TEST RESULTS AVON WASTEWATER TREATMENT FACILITY NUTRIENT UPGRADES

Sample Location Atterberg Limits Swell/Collapse Unconfined Sodium Moisture Dry Density ‐200 Gravel (%) Sand (%) Upon Wetting Compressive Adsorption USCS Soil Or Rock Description Content (%) (pcf) (%) LL PI at 1,000 psf (%) Strength (psf) Ratio Boring No. Sample No. Depth (feet) (%) (%)

Bulk 5.0‐10.0 0.9 SC‐SM silty, clayey SAND C‐4 8.2‐9.2 2.1 112.9 9.4 63.1 27.5 21 6 ‐7.8 SC‐SM silty, clayey SAND BA‐1 MW S‐7 25.0‐26.5 48.8 38.9 12.3 NP NP GM silty GRAVEL with sand S‐10 40.1‐40.4 26.8 21 5 BR SANDSTONE S‐3 12.0‐13.0 63.4 27.3 9.3 GP‐GM poorly graded GRAVEL with silt and sand BA‐2 C‐5 22.0‐23.0 14.1 115.5 70.9 29 11 ‐0.2 9,723 BR SHALE S‐2 4.0‐5.5 42.3 37.1 20.6 24 7 GC‐GM silty, clayey GRAVEL with sand S‐5 15.0‐15.8 28.7 28 6 RS SANDSTONE BA‐4 MW C‐9 30.0‐30.5 2.8 122.8 29 9 ‐1.6 BR SHALE C‐11 40.0‐41.0 11.9 118.0 51.7 28 10 1,015 BR SHALE BA‐5 Bulk 0.0‐9.5 20.8 25 7 ‐ ‐ C‐3 19‐20 55.5 35.3 9.2 NP NP GP‐GM poorly graded GRAVEL with silt and sand BA‐6 S‐6 34‐34.4 59.1 33.6 7.3 GP‐GM poorly graded GRAVEL with silt and sand C‐12 64‐64.5 9.9 130.7 30.9 24 8 903 BR SHALE BA‐7 S‐2 9‐9.8 36.1 48.6 15.3 NP NP SM silty SAND with gravel S‐7 29‐30.5 49.8 39.0 11.2 NP NP GP‐GM poorly graded GRAVEL with silt and sand BA‐8 C‐8 34‐34.8 8.0 131.0 83.1 25 10 5,226 BR SHALE BA‐9 S‐5 24‐25.5 47.5 38.7 13.8 NP NP GM silty GRAVEL with sand

Page 1 TABLE II SUMMARY OF CORROSION TEST RESULTS AVON WASTEWATER TREATMENT FACILITY NUTRIENT UPGRADES

Sample Location Sulfate ‐ Water Chloride ‐ Water Soluble Redox Potential Resistivity AWWA C105 pH (units) Soluble Sulfide USCS Sample (%) (mv) (ohm‐cm) Appendix A Score Boring No. Depth (feet) (%) No. BA‐1 Bulk‐1 5.0‐10.0 7.3 0.0024 279 1,356 0.006 Trace 13.0 SC‐SM BA‐2 C‐1 1.0‐2.0 7.4 0.0101 274 1,986 0.006 Trace 8.0 CL BA‐3 C‐5 22.0‐22.4 7.6 0.0017 247 1,675 0.016 Positive 13.5 BR BA‐4 S‐7 & S‐8 22.0‐25.3 7.8 0.0026 251 1,524 0.003 Positive 13.5 BR BA‐5 Bulk‐1 0.0‐9.5 7.6 0.0029 274.0 1,318 0.011 Positive 14.5 GC‐GC/SC‐SM/RS

Page 1 PROJECT LOCATION

INTERSTATE 70 AVON

HIGHWAY 6

EAGLE VAIL

INTERSTATE 70

HWY 24 BEAVER CREEK

990 S Broadway, Ste 222, Denver, CO 80209 PHONE: 303.703.1405 FAX: 303.703.1404 LEGEND APPROXIMATE TEST BA-# BORING LOCATION APPROXIMATE TEMPORARY MONITORING BA-#MW WELL LOCATION 7377.8 GROUNDWATER ELEVATION (NE=NOT ENCOUNTERED) 7376.8 BA-6 7355 7368.5 BEDROCK ELEVATION

7376.4 BA-7 7368 7377.8 7368.5 BA-1MW

7376.7 DNE 7374 BA-8 BA-9 7380.5

DNE BA-2 7385

DNE BA-3 7382.5

7378.8 BA-4MW 7391

DNE BA-5 DNE

990 S Broadway, Ste 222, Denver, CO 80209 PHONE: 303.703.1405 FAX: 303.703.1404

APPENDIX A Test Boring Key and Test Boring Reports

Boring No. BA-1MW TEST BORING REPORT Sheet No. 1 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 8/6/18 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 8/17/18 Suite 222 Core Driller: Owen/Seth Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek M./Kyle H. Rig Make & Model: Buggy Rig / CME 55 Elevation: 7408' ± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: 6" dia. Solid Stem / ODEX Easting: Hammer Weight (lb.) 140 Bit Type: Cutting Head / ODEX Location: NW corner of Aeration Hammer Fall (in.) 30 Casing:ODEX Basin Addition Water Level Data Sample Identification Notes Boring advanced with solid stem auger Water Date Elapsed Bottom Bottom Depth to to a depth of 11', hole further advanced Level mm/dd/yy Time Time of Casing of Hole Water C California Barrel to termination depth using ODEX. 8/17/18 10:30 30' 29.5 CS Continuous Sampler R Core

8/17/18 3:00 4.5hr 30.2' 29.3 S Split Spoon B Bulk 2/1/19 10:05 30.2 G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

ID structure, odor, moisture,optional descriptions, geologic interpretation Rock: Hardness, weathering, color, LITHOLOGY, texture, Depth (ft.) Depth (ft.) Blows/6 in. Water Level Stratigraphy joint spacing, drilling rate (min./ft.) Elevation Elevation (ft.) Rec.(in. or %)/RQD(%) Rec.(in. or Well Diagram Well (%) Moisture (%) Gravel Sand (%) (%) Fines LL (%) PI (%) UCS (ksf) Swell/Collapse (%) (ksf) Swell Pressure 0 Asphalt Concrete- Approximately 5.5" thick. 0.5 ft. C-1 10 Medium dense, dark brown, silty, clayey GRAVEL (GC-GM), mostly 1.0-2 11 subangular gravel, some silty clay, dry, no odor. 12" -ALLUVIUM- 7405 C-2 14 Very stiff, yellowish brown, SILTY CLAY with sand (CL-ML), mostly 3.5-4 50/0" silt clay, little sand, little gravel, no odor, dry, cobbles/boulders 5 6" apparent. -ALLUVIUM- 5.0 ft. C-3 50/2" Very dense, light brown to tan, silty, clayey SAND (SC-SM), mostly 6.0-6.2 fine to coarse sand, little to some silty clay, few gravel, dry, no odor, 2" cobbles/boulders apparent. 7400 -ALLUVIUM- C-4 21 As above, except medium dense. 2.1 9.4 63.1 27.5 21 6 -7.8 8.2-9.2 14 12" 10

11.0' - Practical refusal with solid stem augers due to boulders. 11.0 ft. 11.0' to 13.0' - ODEX cutting dust is gray, chips in cuttings consist of gneissic rock. 7395 13.0' to 20.0' - ODEX cutting dust alternates between red and light gray color, gravel consists of gneiss and red granitic rock, indicative of boulders. 15 S-5 50/3" No recovery with split spoon sampler. 15.0-15.3 0"

7390

20 S-6 100/4" Very dense, brown, gray, and red, silty GRAVEL with sand (GM), 20.0-20.3 some fine to coarse, subrounded gravel, some fine to coarse sand, 3" few to little silt, no odor, moist.

-ALLUVIUM- 7385

25 S-7 25 As above, except gravel is subrounded to subangular. 48.8 38.9 12.3 NP NP 25.0-26.5 45 14" 26

7380

Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-1MW NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-1MW TEST BORING REPORT Sheet No. 2 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 8/6/18 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 8/17/18 Suite 222 Core Driller: Owen/Seth Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek M./Kyle H. Rig Make & Model: Buggy Rig / CME 55 Elevation: 7408' ± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: 6" dia. Solid Stem / ODEX Easting: Hammer Weight (lb.) 140 Bit Type: Cutting Head / ODEX Location: NW corner of Aeration Hammer Fall (in.) 30 Casing:ODEX Basin Addition Water Level Data Sample Identification Notes Boring advanced with solid stem auger Water Date Elapsed Bottom Bottom Depth to to a depth of 11', hole further advanced Level mm/dd/yy Time Time of Casing of Hole Water C California Barrel to termination depth using ODEX. 8/17/18 10:30 30' 29.5 CS Continuous Sampler R Core

8/17/18 3:00 4.5hr 30.2' 29.3 S Split Spoon B Bulk 2/1/19 10:05 30.2 G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

30 S-8 50/0" No recovery with split spoon sampler, autohammer ringing during 30.0-30 sampling, indicative of hard boulder. 0" 30.0' to 35.0' - ODEX cuttings consist of black, red, white, and brown rock fragments, indicative of boulders/cobbles

7375

35 S-9 21 Medium dense, brown and gray, silty GRAVEL with sand (GM), 35.0-36.5 16 mostly fine to coarse subrounded to subangular gravel, little sand, 11" 14 little silt, no odor, wet, gravel consists of igneous rock and shale. 35.0' to 39.0' - ODEX cuttings consist of red, white, and brown rock chips, indicative of boulders/cobbles. 7370

39.5 ft. 40 S-10 50/5" Very soft, completely weathered, olive brown and gray, SILTSTONE, 26.8 21 5 40.0-40.4 mostly silt, little fine sand, uncemented, wet. 15" -EAGLE VALLEY FORMATION- 40.1 ft. Very soft, moderately weathered, gray, SANDSTONE (BR), mostly fine sand, little to some silty clay, very closely spaced jointing, 7365 weakly cemented, wet, low-medium plasticity. -EAGLE VALLEY FORMATION- 40.4 ft. End of drilling. 45

7360

7355

7350 Boring No. BA-2 TEST BORING REPORT Sheet No. 1 of 1 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 8/17/18 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 8/17/18 Suite 222 Core Driller: Owen Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7405' ± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: SE corner of Aeration Basin Hammer Fall (in.) 30 Casing:ODEX Addition Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 8/17/18 2:00 23' DNE CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

5 7400

6.0 ft.

S-2 50/6" Very dense, brown, black, pink, and white, well-graded GRAVEL with 7.0-7.5 sand (GW), mostly rounded to angular gravel, little sand, trace silt, 3" no odor, dry, sample possibly representative of cobble or boulder fragments. -ALLUVIUM- 10 7395 7.0' to 12.0' - Chips in ODEX cuttings consist of gneiss and granitic rock fragments.

S-3 40 12.0 ft. 63.4 27.3 9.3 Very dense, black, gray, and brown, poorly graded GRAVEL with silt 12.0-13 50/6" and sand (GP-GM), mostly fine to coarse gravel, little sand, few silt, 7" no odor, dry. -ALLUVIUM- 12.0' to 17.0' - Chips in ODEX cuttings consist of gneiss and granitic 15 7390 rock fragments.

S-4 50/3" As above, except some sand, gravel consists of rounded to 17.0-17.3 subangular, strongly cemented sandstone, granitic rock, and quartz 3" fragments.

20 7385 20.0 ft. 20.0' - ODEX cuttings are light brown, consisting of fines and shale fragments. -EAGLE VALLEY FORMATION- C-5 28 Very soft to medium hard, moderately weathered, gray and olive 14.1 70.9 29 11 9.7 -0.2 22.0-23 50 brown, very fine grained, SHALE (BR), mostly clay, little fine sand, 12" no odor, moist, platy, weakly to strongly indurated. 23.0 ft. End of drilling. 25 7380

Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-2 NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-3 TEST BORING REPORT Sheet No. 1 of 1 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 8/17/18 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 8/17/18 Suite 222 Core Driller: Owen Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7404' ± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: West side of Secondary Hammer Fall (in.) 30 Casing:ODEX Clarifier 3 Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 8/17/18 3:45 27.3' DNE CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

S-1 50/5" Very dense, white and pink, silty GRAVEL (GM), mostly gravel, little 2.0-2.3 sand, little silt, no odor, dry, sample indicative of boulders/cobbles 3" present. 7400 -ALLUVIUM-

6.0 ft.

S-2 19 Dense, red, gray, brown, black, silty SAND with gravel (SM), some 7.0-7.8 27 fine to coarse sand, some gravel, little silt, no odor, dry. 10" 15 7395 -ALLUVIUM-

S-3 50/0" 12.0 ft. No recovery with split spoon sampler. 12.0-12 12.0' to 15.0' - Chips in ODEX cuttings consist of gneiss and granitic 0" rock, indicative of boulders/cobbles present. 7390

S-4 24 Very dense, brown, black, and red, silty GRAVEL with sand (GM), 17.0-17.9 50/5" some gravel, some sand, little silt, no odor, dry, sample indicative of 4" boulders/cobbles present. 7385 -ALLUVIUM- 20

21.5 ft. C-5 50/4" 21.5' - ODEX dust changes color from brown to gray. Very soft to medium hard, moderately weathered, brown and gray, 22.0-22.4 SHALE (BR), mostly silt, claystone interbeds present, no odor, moist, 4" weakly to strongly indurated. 7380 -EAGLE VALLEY FORMATION- 25

C-6 100/3" No recovery with Modified California sampler. 27.0-27.3 27.3 ft. 0" End of drilling. Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-3 NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-4MW TEST BORING REPORT Sheet No. 1 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 8/13/18 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 8/13/18 Suite 222 Core Driller: Owen Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7404' ± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: SE corner of Secondary Hammer Fall (in.) 30 Casing:ODEX Clarifier 3 Water Level Data Sample Identification Notes Breakdown of Shale did not occur during Water Date Elapsed Bottom Bottom Depth to Time testing of sample C-9. Level mm/dd/yy Time of Casing of Hole Water C California Barrel 8/13/18 10:30 22.3' 22' CS Continuous Sampler R Core

8/17/18 8:15 48' 22.3' S Split Spoon B Bulk 2/2/19 12:00 48' 25.2' G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

C-3 44 7.0 ft. Very dense, light brown, silty GRAVEL with sand (GM), some fine to 7.0-8 29 coarse, subangular to subrounded gravel, little fine to coarse sand, 10" little silt, no odor, dry, cobble fragment in sampler shoe. 7395 S-4 4 9.0-10.5 3 -ALLUVIUM- 10 1" 3 As above, except loose.

13.0 ft. 13.0' - ODEX dust color changes from brown to red. 7390

15 S-5 30 Very soft to soft, completely weathered, reddish brown, silty, clayey 28.7 28 6 15.0-15.8 50/3" SANDSTONE, moderately cemented, extremely thin shale interbeds 14" present, no odor, dry, low to medium plasticity. -EAGLE VALLEY FORMATION- 17.0 ft. 17.0' - ODEX dust color changes from red to gray. -EAGLE VALLEY FORMATION- 7385

20 S-6 50/3" No recovery with split spoon sampler. 20.0-20.3 0" S-7 50/3" Soft to medium hard, fresh, dark gray, fine-grained, platy to papery, 22.0-22.3 SHALE, very closely spaced jointing, moderately to strongly 3" cemented, wet, low to medium plasticity. 7380

25 S-8 50/3" As above, except moist. 25.0-25.3 3"

Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-4MW NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-4MW TEST BORING REPORT Sheet No. 2 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 8/13/18 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 8/13/18 Suite 222 Core Driller: Owen Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7404' ± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: SE corner of Secondary Hammer Fall (in.) 30 Casing:ODEX Clarifier 3 Water Level Data Sample Identification Notes Breakdown of Shale did not occur during Water Date Elapsed Bottom Bottom Depth to Time testing of sample C-9. Level mm/dd/yy Time of Casing of Hole Water C California Barrel 8/13/18 10:30 22.3' 22' CS Continuous Sampler R Core

8/17/18 8:15 48' 22.3' S Split Spoon B Bulk 2/2/19 12:00 48' 25.2' G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

30 C-9 50/6" As above, except medium plasticity. 2.8 29 9 -1.6 30.0-30.5 6"

7370

35 C-10 100/4" As above, except hard, strongly cemented, wet, sample consists of 35.0-35.4 broken shale fragments. 2"

7365

40 C-11 26 As above, except very soft to medium hard, black, weakly to 11.9 51.7 28 10 1.0 40.0-41 28 moderately cemented. 12"

7360

45 C-12 50/4" As above. 45.0-45.4 4"

48.0 ft. End of drilling. 7355

7350

7345 Boring No. BA-5 TEST BORING REPORT Sheet No. 1 of 1 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 8/6/18 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 8/6/18 Suite 222 Core Driller: Seth Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Kyle Hinds Rig Make & Model: CME 750 Buggy Elevation: 7395' ± Type NA C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 2, 1.5 Drill Method: Solid Stem Auger Easting: Hammer Weight (lb.) 140 Bit Type: Cutting Head Location: South of existing historic Hammer Fall (in.) 30 Casing:NA barn Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 8/6/18 2:00 10' DNE CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

C-1 23 Dense, brown to dark brown, silty, clayey GRAVEL with sand (GC- 1.0-2 23 GM), some gravel, some sand, little silty clay, dry, no odor, with 12" boulders. -FILL- 2.0' - 3" bolt in cuttings. C-2 18 As above. 3.5-4.5 35 5 7390 6"

C-3 9 6.0 ft. Medium dense, brown, silty, clayey SAND with gravel (SC-SM), 6.0-7 24 mostly fine sand, some gravel, little silt/clay, moist, no odor, trace 10" white powdery evaporite streaks that dissolve in H2O. -ALLUVIUM- C-4 4 As above. 8.5-9.5 11 9.3 ft. 10 7385 12" Very soft, highly weathered, light tan, SILTSTONE (BR), mostly silt, some fine sand, platy, no odor, dry. -RESIDUUM- 9.5 ft. End of drilling.

15 7380

20 7375

25 7370

Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-5 NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-6 TEST BORING REPORT Sheet No. 1 of 3 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/2/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/2/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME-55 Elevation: 7412' Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: Proposed Crane Pad Hammer Fall (in.) 30 Casing:ODEX Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 2/2/19 11:30 40' 40' 35.2' CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

7410 -FILL-

7405

S-1 34 Very dense, brown and pink, silty, clayey, GRAVEL (GC-GM) with 9.0-10.5 36 sand, mostly fine to coarse gravel, some sand, some silty clay, 10 12" 40 moist.

-FILL- 7400

S-2 50/6" 14 ft. Very dense, brown and white, poorly graded GRAVEL with silt and 14.0-14.5 15 sand (GP-GM) , mostly fine to coarse quartz and gneiss gravel, 6" some fine to coarse sand, few silt, moist, HCl reaction.

-ALLUVIUM- 7395

C-3 40 As above, HCl reaction. 55.5 35.3 9.3 NP NP 19.0-20 36 20 8"

7390

S-4 50/3" Limited recovery, sample consisted of coarse angular granitic rock 24.0-24.3 fragment with potassium feldspar and biotite crystals. 25 3"

7385

Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-6 NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-6 TEST BORING REPORT Sheet No. 2 of 3 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/2/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/2/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME-55 Elevation: 7412' Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: Proposed Crane Pad Hammer Fall (in.) 30 Casing:ODEX Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 2/2/19 11:30 40' 40' 35.2' CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

7380

S-6 50/5" As above, except white, red, and black, HCL reaction. 34.0-34.4 35 3"

7375

40 S-7 50/0" No recovery with split spoon sampler, no sampler advancement, 40.0-40 likely drove on boulder. 0" 7370

45 S-8 31 As above, except red, black, and tan, wet, most of sample was 45.0-46.5 38 decomposed boulder, tip of sample contained quartzite gravel. 12" 43 7365 47' to 48' - ODEX cuttings became light brown and were moist rather than wet.

S-9 50/2" 49 ft. Very dense, red, black, and brown, silty SAND (SM) with gravel, 49.0-49.2 50 mostly fine to coarse sand, some fine to coarse gravel, little silt, wet, 2" no HCl reaction. -ALLUVIUM- 49.2' to 54' - ODEX cuttings were wet and chips contain red, white, 7360 and black gneiss, quartz, and granitic rock fragments.

S-10 50/0" No recovery with split spoon sampler, likely drove sampler on 54.0-54 boulder. 55 0"

7355 57 ft. 57' - ODEX cuttings became black shale fragments and were moist. -EAGLE VALLEY FORMATION-

C-11 50/1" Soft, fresh, black, very fine-grained, SHALE (BR), blocky, moist, Boring No. BA-6 TEST BORING REPORT Sheet No. 3 of 3 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/2/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/2/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME-55 Elevation: 7412' Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: Proposed Crane Pad Hammer Fall (in.) 30 Casing:ODEX Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 2/2/19 11:30 40' 40' 35.2' CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

-EAGLE VALLEY FORMATION- 7350

C-12 50/5" As above. 64.0-64.4 64.4 ft. 9.9 30.9 24 8 0.9 65 5" End of drilling.

7345

7340

7335

7330

7325 Boring No. BA-7 TEST BORING REPORT Sheet No. 1 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/1/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/2/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7409'± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: North side of Aeration Basin Hammer Fall (in.) 30 Casing:ODEX Addition Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 02/02/19 08:30 34' 34.7' 32.6' CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

7405 S-1 8 Hard, dark brown, LEAN CLAY (CL) with sand and gravel, mostly 4.0-4.8 50/4" lean clay, little fine sand, few fine rounded gravel, no odor, moist. 5 10" -FILL- 6 ft.

7400 S-2 27 Very dense, dark brown, white, red, silty SAND (SM) with gravel, 36.1 48.6 15.3 NP NP 9.0-9.8 50/3" mostly sand, little silt, some fine to coarse gravel consisting of quartz 10 7" and granitic rock, no odor, moist, HCl reaction.

-ALLUVIUM- 12 ft. 12' to 14' - ODEX cuttings consist of gray fines and chips of quartz and granitic rock.

7395 C-3 50/3" No recovery with California sampler. 14.0-14.3 15 0"

7390 S-4 50/6" Very dense, gray, black white, silty GRAVEL (GM), mostly coarse 19.0-19.5 gravel consisting of gneiss, little silt, little sand, sampler was ringing, 20 2" indicative of cobbles/boulder, HCl reaction.

7385 S-5 50/5" As above, HCl reaction. 24.0-24.4 25 24.4' to 29' - ODEX cuttings consist of fines and chips of gneiss and 2" granitic rock, HCl reaction.

Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-7 NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-7 TEST BORING REPORT Sheet No. 2 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/1/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/2/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7409'± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: North side of Aeration Basin Hammer Fall (in.) 30 Casing:ODEX Addition Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 02/02/19 08:30 34' 34.7' 32.6' CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

7375 S-7 40 As above, except some sand, wet, no HCl reaction. 34.0-34.7 60/2" 35 4"

7370 S-8 14 As above, except few sand, brown, platy, highly weathered shale 39.0-40.5 38 gravel in shoe. 40 6" 17 41 ft. 41' to 42' - Driller notes change in drilling consistency, ODEX cuttings consist of brown shale. Very soft, moderately weathered, gray and olive brown, very fine- grained to fine-grained, SHALE (BR), mostly silty clay, little fine 7365 sand, platy, moist, weakly cemented, shale fragments were non- C-9 50/3" reactive with HCl, but pulverized fines were reactive with HCl. 44.0-44.3 45 -EAGLE VALLEY FORMATION- 2" 44.3 ft. End of drilling.

7360

7355

7350 Boring No. BA-8 TEST BORING REPORT Sheet No. 1 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/1/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/1/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7406'± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: West side of Aeration Basin Hammer Fall (in.) 30 Casing:ODEX Addition Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 02/01/19 2:45 - 30' 30' CS Continuous Sampler R Core

02/02/19 09:15 - 30' 29.3' S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

7405

C-1 23 Hard, brown, LEAN CLAY (CL) with sand and gravel, mostly lean 4.0-5 18 clay, little rounded to subangular quartz and gneiss gravel, little 5 7" sand, moist. 7400 -FILL-

7.5 ft.

S-2 50/5" Very dense, white, red, and brown silty GRAVEL (GM) with sand, 9.0-9.4 mostly rounded to subangular or gneiss and granitic gravel, little 10 2" sand, little silt, no odor, dry. 7395 -ALLUVIUM-

S-3 50/2" No recovery with split spoon sampler. 14.0-14.2 14.2' to 19' - ODEX cuttings consist of sand particles and chips of 15 0" quartz, gneiss, shale, and granitic rock. 7390 B-4 14.2-19 57"

18 ft.

S-5 50/3" Very dense, black, white, brown, silty SAND (SM) with gravel, mostly 19.0-19.3 fine to coarse sand, little silt, little gravel consisting of gneiss and 20 1" siltstone gravel, no odor, dry, HCl reaction. 7385 -ALLUVIUM- 19.3' to 24' - cuttings consist of sand particles and chips of granite rock and gneiss.

S-6 50/3" As above, except with granitic gravel, moist, HCl reaction. 24.0-24.3 25 2" 7380

Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-8 NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-8 TEST BORING REPORT Sheet No. 2 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/1/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/1/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7406'± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: West side of Aeration Basin Hammer Fall (in.) 30 Casing:ODEX Addition Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 02/01/19 2:45 - 30' 30' CS Continuous Sampler R Core

02/02/19 09:15 - 30' 29.3' S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

32 ft. 32' - ODEX dust changes to brown color and contains shale fragments.

C-8 39 Very soft, fresh, dark gray, very fine-grained, SHALE (BR), platy, 8.0 83.1 25 10 5.2 34.0-34.8 50/4" moist, no HCl reaction. 35 8" -EAGLE VALLEY FORMATION- 7370 34.8' to 39.2' - ODEX cuttings consist of low to medium plasticity fines and gray shale fragments, no HCl reaction.

S-9 50/2" No recovery with split spoon sampler. 39.0-39.2 39.2 ft. 40 0" End of drilling. 7365

7360

7355

7350 Boring No. BA-9 TEST BORING REPORT Sheet No. 1 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/1/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/1/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7407'± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: East side of Aeration Basin Hammer Fall (in.) 30 Casing:ODEX Addition Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 2/1/19 10:15 35' 35' DNE CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

7405

S-1 24 Very dense, brown, white, and black, silty, clayey GRAVEL (GC-GM) 4.0-5 50/6" with sand, mostly subrounded to angular gravel, some silty clay, little 5 7" sand, no odor, moist, rootlets and brick fragments present.

-FILL- 7400 7 ft. 7' to 9' - ODEX chips consist of red granite, rocky gneiss and shale. -ALLUVIUM-

S-2 50/1" No recovery with split spoon sampler at 9'. 9.0-9.1 9.1' to 14'- ODEX chips consist of fines, sand, and red, black, and 10 0" white granitic rock, gneiss and shale. Driller reports upper half of run was harder and lower half of run was relatively less hard.

7395

C-3 50/5" No recovery with California sampler at 14'. 14.0-14.5 15 14.5' to 19' - ODEX chips consist primarily of gneiss fragments with 0" occasional granitic and quartz fragments.

7390

S-4 50/5" Very dense, brown, red, and black, well-graded SAND (SW) with silt 19.0-19.5 and gravel, mostly fine to coarse sand, few to little silt, some 20 3" subrounded to subangular gravel consisting of granitic rock and gneiss, dry. 19.5' to 24' - Driller reports relatively easier drilling, chips are moist, 7385 and consist of granitic rock fragments and gneiss fragments.

S-5 30 24 ft. 47.5 38.7 13.8 NP NP Very dense, brown, black and maroon, silty GRAVEL (GM) with 24.0-25.5 40 25 sand, some fine to coarse sand, little silt, mostly gravel, dry. 14" 43 -ALLUVIUM- C-6 24 50/5" No recovery with California sampler. 25.5-26.4 26.5 ft. 7380 0" 26.5' - ODEX dust becomes light brown and advancement becomes easier.

Maximum particle size is determined by direct observation within the limitations of the sampler. Boring No: BA-9 NOTE: Soil identification based on visual-manual methods of the USCS as practiced by Brierley Associates. Boring No. BA-9 TEST BORING REPORT Sheet No. 2 of 2 Project: Avon WWTF Nutrient Upgrade Project File No. 518065-000 Client: Carollo Start: 2/1/19 990 S. Broadway Drilling Contractor: Vine Laboratories Finish: 2/1/19 Suite 222 Core Driller: Owen Potter Denver, Colorado 80209 Casing Sampler Barrel Drilling Equipment and Procedures BA Rep.: Derek Magnuson Rig Make & Model: CME 55 Elevation: 7407'± Type ODEX C, S Hoist/Hammer: Automatic Northing: Inside Diameter (in.) 4 2, 1.5 Drill Method: ODEX Easting: Hammer Weight (lb.) 140 Bit Type: ODEX Location: East side of Aeration Basin Hammer Fall (in.) 30 Casing:ODEX Addition Water Level Data Sample Identification Notes

Water Date Elapsed Bottom Bottom Depth to Time Level mm/dd/yy Time of Casing of Hole Water C California Barrel 2/1/19 10:15 35' 35' DNE CS Continuous Sampler R Core

S Split Spoon B Bulk G Geoprobe T Thin Wall Tube Visual-Manual Identification and Description Laboratory Results

Soil: Density/consistency, color, GROUP NAME, max. particle size,

ID structure, odor, moisture,optional descriptions, geologic interpretation Rock: Hardness, weathering, color, LITHOLOGY, texture, Depth (ft.) Depth (ft.) Blows/6 in. Water Level Stratigraphy joint spacing, drilling rate (min./ft.) Elevation Elevation (ft.) Rec.(in. or %)/RQD(%) Rec.(in. or Well Diagram Well (%) Moisture (%) Gravel Sand (%) (%) Fines LL (%) PI (%) UCS (ksf) Swell/Collapse (%) (ksf) Swell Pressure S-7 50/1" Soft, highly weathered, brown, very fine-grained, SHALE, platy, 29.0-29.1 mostly clay, little fine sand, weakly to strongly cemented, dry. 30 1" -EAGLE VALLEY FORMATION- B-8 29.5' to 32' - ODEX cuttings consist of soft black shale chips and 29.5-32 black silty clay with sand. 7375 30" B-9 32' - ODEX cuttings are light brown, consisting of fines and weakly to 32.0-34 strongly cemented shale fragments. 24" C-10 50/1" No recovery with California sampler; sampler bouncing. 34.0-34.1 34.1 ft. 35 0" End of drilling.

7370

7365

7360

7355

7350

APPENDIX B Laboratory Testing Results

Particle Size Distribution Report 6in. 3in. 2in. in.1½ 1in. in.¾ in.½ 3/8in. #4 #10 #20 #30 #40 #60 #100 #140 #200 100

40 PERCENT FINER PERCENT

0 100 10 1 0.1 0.01 0.001 GRAIN SIZE - mm.

+3" % GRAVEL % SAND % SILT % CLAY USCS LL PL PI 0.0 9.4 63.1 27.5 SC-SM 21 15 6 0.0 48.8 38.9 12.3 GM NV NP NP 21 16 5

SIEVE PERCENT FINER SIEVE PERCENT FINER Material Description inches number USCS: silty, clayey sand size size 1.5" 100.0 #4 90.6 51.2 1" 93.8 #10 77.7 42.5 USCS: silty gravel with sand 3/4" 100.0 91.3 #20 63.0 34.3 1/2" 95.6 73.2 #40 50.0 25.2 3/8" 93.4 63.4 #60 42.0 19.2 #100 34.5 15.1 #200 27.5 12.3 26.8 GRAIN SIZE REMARKS: D60 0.7261 8.2634 D30 0.0993 0.6081 D10 COEFFICIENTS Cc Cu Location: BA-1 C-4 Depth: 8.5-9.5' Sample Number: 7263 Location: BA-1 S-7 Depth: 25-26.5' Sample Number: 7264 Location: BA-1 S-10 Depth: 40.1-40.4' Sample Number: 7265 Client: Brierley Associates Project: Avon WWTP BA 518065-000 Project No.: 18-0109 Figure Particle Size Distribution Report 6in. 3in. 2in. in.1½ 1in. in.¾ in.½ 3/8in. #4 #10 #20 #30 #40 #60 #100 #140 #200 100

40 PERCENT FINER PERCENT

0 100 10 1 0.1 0.01 0.001 GRAIN SIZE - mm.

+3" % GRAVEL % SAND % SILT % CLAY USCS LL PL PI 0.0 63.4 27.3 9.3 29 18 11 0.0 42.3 37.1 20.6 GC-GM 24 17 7

SIEVE PERCENT FINER SIEVE PERCENT FINER Material Description inches number size size 1.5" 100.0 100.0 #4 36.6 57.7 1" 83.4 94.6 #10 28.6 50.0 3/4" 67.4 85.0 #20 22.4 41.9 1/2" 56.4 72.7 #40 17.6 34.4 3/8" 50.0 67.1 #60 14.5 29.1 USCS: silty clayey gravel with sand #100 11.8 24.3 #200 9.3 70.9 20.6 GRAIN SIZE REMARKS: D60 15.1777 5.7982 D30 2.4531 0.2740 D10 0.0933 COEFFICIENTS Cc 4.25 Cu 162.72 Location: BA-2 S-3 Depth: 12-13' Sample Number: 7266 Location: BA-2 C-5 Depth: 22-23' Sample Number: 7267 Location: BA-4 S-2 Depth: 4-5.5' Sample Number: 7268 Client: Brierley Associates Project: Avon WWTP BA 518065-000 Project No.: 18-0109 Figure Particle Size Distribution Report 6in. 3in. 2in. in.1½ 1in. in.¾ in.½ 3/8in. #4 #10 #20 #30 #40 #60 #100 #140 #200 100

40 PERCENT FINER PERCENT

0 100 10 1 0.1 0.01 0.001 GRAIN SIZE - mm.

+3" % GRAVEL % SAND % SILT % CLAY USCS LL PL PI 28 22 6 29 20 9 28 18 10

SIEVE PERCENT FINER SIEVE PERCENT FINER Material Description inches number size size #200 28.7 9.6 51.7

GRAIN SIZE REMARKS: D60 D30 D10 COEFFICIENTS Cc Cu Location: BA-4 S-5 Depth: 15-15.8' Sample Number: 7269 Location: BA-4 C-9 Depth: 30-30.5' Sample Number: 7270 Location: BA-4 C-11 Depth: 40-41' Sample Number: 7271 Client: Brierley Associates Project: Avon WWTP BA 518065-000 Project No.: 18-0109 Figure Particle Size Distribution Report 6in. 3in. 2in. in.1½ 1in. in.¾ in.½ 3/8in. #4 #10 #20 #30 #40 #60 #100 #140 #200 100

40 PERCENT FINER PERCENT

0 100 10 1 0.1 0.01 0.001 GRAIN SIZE - mm.

+3" % GRAVEL % SAND % SILT % CLAY USCS LL PL PI 25 18 7

SIEVE PERCENT FINER SIEVE PERCENT FINER Material Description inches number size size #200 20.8

GRAIN SIZE REMARKS: D60 D30 D10 COEFFICIENTS Cc Cu Location: BA-5 Bulk Depth: 0-10' Sample Number: 7272

Client: Brierley Associates Project: Avon WWTP BA 518065-000 Project No.: 18-0109 Figure Particle Size Distribution Report 6in. 3in. 2in. in.1½ 1in. in.¾ in.½ 3/8in. #4 #10 #20 #30 #40 #60 #100 #140 #200 100

40 PERCENT FINER PERCENT

0 100 10 1 0.1 0.01 0.001 GRAIN SIZE - mm.

+3" % GRAVEL % SAND % SILT % CLAY USCS LL PL PI 0.0 55.5 35.3 9.2 GP-GM NV NP NP 0.0 59.1 33.6 7.3 24 16 8

SIEVE PERCENT FINER SIEVE PERCENT FINER Material Description inches number USCS: poorly graded gravel with silt and sand size size 1.5" 100.0 100.0 #4 44.5 40.9 1" 77.1 89.4 #10 37.0 30.4 3/4" 70.6 70.7 #20 28.3 23.0 1/2" 62.5 60.5 #40 18.5 17.3 3/8" 55.5 55.3 #60 14.3 13.8 #100 11.7 10.4 #200 9.2 7.3 30.9 GRAIN SIZE REMARKS: D60 11.4782 12.2529 D30 0.9700 1.9108 D10 0.0959 0.1397 COEFFICIENTS Cc 0.85 2.13 Cu 119.70 87.70 Location: BA-6 Depth: 19-20' Sample Number: 7540 Location: BA-6 Depth: 34-34.4' Sample Number: 7541 Location: BA-6 Depth: 64-64.5' Sample Number: 7542 Client: Brierley Associates Project: Avon WWTF BA 518065-000 Project No.: 18-0109 Figure Particle Size Distribution Report 6in. 3in. 2in. in.1½ 1in. in.¾ in.½ 3/8in. #4 #10 #20 #30 #40 #60 #100 #140 #200 100

40 PERCENT FINER PERCENT

0 100 10 1 0.1 0.01 0.001 GRAIN SIZE - mm.

+3" % GRAVEL % SAND % SILT % CLAY USCS LL PL PI 0.0 36.1 48.6 15.3 SM NV NP NP 0.0 49.8 39.0 11.2 GP-GM NV NP NP 25 15 10

SIEVE PERCENT FINER SIEVE PERCENT FINER Material Description inches number USCS: silty sand with gravel size size 1.5" 100.0 100.0 #4 63.9 50.2 1" 92.4 89.0 #10 53.4 39.9 USCS: poorly graded gravel with silt and sand 3/4" 89.4 85.4 #20 37.4 27.5 1/2" 73.4 71.0 #40 27.1 20.8 3/8" 70.4 65.2 #60 22.3 16.7 #100 18.7 13.7 #200 15.3 11.2 83.1 GRAIN SIZE REMARKS: D60 3.3337 7.4162 D30 0.5359 1.0183 D10 COEFFICIENTS Cc Cu Location: BA-7 Depth: 9-9.8' Sample Number: 7543 Location: BA-8 Depth: 29-30.5' Sample Number: 7544 Location: BA-8 Depth: 34-34.8' Sample Number: 7545 Client: Brierley Associates Project: Avon WWTF BA 518065-000 Project No.: 18-0109 Figure Particle Size Distribution Report 6in. 3in. 2in. in.1½ 1in. in.¾ in.½ 3/8in. #4 #10 #20 #30 #40 #60 #100 #140 #200 100

40 PERCENT FINER PERCENT

0 100 10 1 0.1 0.01 0.001 GRAIN SIZE - mm.

+3" % GRAVEL % SAND % SILT % CLAY USCS LL PL PI 0.0 47.5 38.7 13.8 GM NV NP NP

SIEVE PERCENT FINER SIEVE PERCENT FINER Material Description inches number USCS: silty gravel with sand size size 1.5" 100.0 #4 52.5 1" 90.8 #10 42.2 3/4" 84.1 #20 34.3 1/2" 72.0 #40 26.8 3/8" 65.2 #60 21.4 #100 17.1 #200 13.8 GRAIN SIZE REMARKS: D60 7.3645 D30 0.5672 D10 COEFFICIENTS Cc Cu Location: BA-9 Depth: 24-25.5' Sample Number: 7546

Client: Brierley Associates Project: Avon WWTF BA 518065-000 Project No.: 18-0109 Figure Martinez Associates 14828 West 6th Avenue, Unit 9-B Golden, Colorado 80401 Phone: (303) 459-2216 Fax: (303) 482-2230 One Dimensional Collapse (ASTM D 4546) (Denver Area Swell/Consolidation Test) Client Project No.: 518065-000 Proj. Name: Avon WWTF Sampled By: BA Martinez Job No.: 18-0109 Lab Tech: WS Greer Test Date: 8/22/18 Sample Date: NP Sample ID: 7263 Reviewed By: K. Runner Sample Location: BA-1 C-4 at 8.5-9.5' Soil Description: USCS: Silty Clayey Sand USCS: SC-SM

Sample Data: Ring No: C Dish No: 23 Ring Mass (g): 276.8 Dish Mass (g): 8 Sample Height (in): 0.75 Swell Machine #: 3 Pre-test Sample Post-test Sample Ring + Sample (g): 343.6 Ring + Sample (g): 351.4 Dish wt: 8.0 Dish wt: 108.2 Wet wt (g): 324.0 Wet wt (g): 184.0 Dry wt (g): 317.4 Dry wt (g): 175.3

Results: Moisture/Density Pre-test Sample Post-test Sample Moisture Content: 2.1% Moisture Content: 13.0% Wet Density (pcf): 115.3 Wet Density (pcf): 144.5 Dry Density (pcf): 112.9 Dry Density (pcf): 127.9

Swell/Consolidation Load (ksf): 0.1 1 Add Water 1 2 Correction (x 10-4): 0 33 33 55 Dial Reading (x 10-4): 4248 4143 3561 3373 Swell/Consolidation %: 0.0% -1.0% -8.7% -10.9% Results: Collapse Upon Wetting @ Tested By: WS Greer -7.8% 1000 psf: Checked By:K. Runner Swell Pressure (psf): NA

Swell/Consolidation Plot 0.0%

-1.0% -2.0% -3.0% -4.0% -5.0% -6.0% Inundated -7.0% -8.0% -9.0% -10.0% -11.0% Swell / Consolidation (%) /ConsolidationSwell -12.0% 0.1 1 10 Applied Pressure (ksf) Martinez Associates 14828 West 6th Avenue, Unit 9-B Golden, Colorado 80401 Phone: (303) 459-2216 Fax: (303) 482-2230 One Dimensional Swell/Consolidation (ASTM D 4546) (Denver Area Swell/Consolidation Test) Client Project No.: 518065-000 Proj. Name: Avon WWTF Sampled By: BA Martinez Job No.: 18-0109 Lab Tech: WS Greer Test Date: 8/22/18 Sample Date: NP Sample ID: 7267 Reviewed By: K. Runner Sample Location: BA-2 C-5 at 22-23' Soil Description: USCS:

Sample Data: Ring No: D Dish No: 25 Ring Mass (g): 238.2 Dish Mass (g): 7.9 Sample Height (in): 0.75 Swell Machine #: 4 Pre-test Sample Post-test Sample Ring + Sample (g): 314.6 Ring + Sample (g): 316.4 Dish wt: 7.9 Dish wt: 103.5 Wet wt (g): 349.5 Wet wt (g): 181.5 Dry wt (g): 307.2 Dry wt (g): 169.4

Results: Moisture/Density Pre-test Sample Post-test Sample Moisture Content: 14.1% Moisture Content: 18.4% Wet Density (pcf): 131.8 Wet Density (pcf): 137.9 Dry Density (pcf): 115.5 Dry Density (pcf): 116.5

Swell/Consolidation Load (ksf): 0.1 1 Add Water 1 2 Correction (x 10-4): 0 33 33 56 Dial Reading (x 10-4): 3916 3818 3800 3700 Swell/Consolidation %: 0.0% -0.9% -1.1% -2.1% Results: Settlement Upon Wetting @ Tested By: WS Greer -0.2% 1000 psf: Checked By:K. Runner Swell Pressure (psf): NA

Swell/Consolidation Plot 0.0%

-1.0%

Inundated

-2.0% Swell / Consolidation (%) /ConsolidationSwell -3.0% 0.1 1 10 Applied Pressure (ksf) Martinez Associates 14828 West 6th Avenue, Unit 9-B Golden, Colorado 80401 Phone: (303) 459-2216 Fax: (303) 482-2230 One Dimensional Swell/Consolidation (ASTM D 4546) (Denver Area Swell/Consolidation Test) Client Project No.: 518065-000 Proj. Name: Avon WWTF Sampled By: BA Martinez Job No.: 18-0109 Lab Tech: WS Greer Test Date: 8/22/18 Sample Date: NP Sample ID: 7270 Reviewed By: K. Runner Sample Location: BA-4 C-9 at 30-30.5' Soil Description: USCS:

Sample Data: Ring No: E Dish No: 56 Ring Mass (g): 238.0 Dish Mass (g): 8 Sample Height (in): 0.75 Swell Machine #: 5 Pre-test Sample Post-test Sample Ring + Sample (g): 311.2 Ring + Sample (g): 316.1 Dish wt: 8.0 Dish wt: 103.2 Wet wt (g): 287.4 Wet wt (g): 180.7 Dry wt (g): 279.7 Dry wt (g): 172.2

Results: Moisture/Density Pre-test Sample Post-test Sample Moisture Content: 2.8% Moisture Content: 12.3% Wet Density (pcf): 126.3 Wet Density (pcf): 139.8 Dry Density (pcf): 122.8 Dry Density (pcf): 124.5

Swell/Consolidation Load (ksf): 0.1 1 Add Water 1 2 Correction (x 10-4): 0 33 33 55 Dial Reading (x 10-4): 3093 2985 2868 2768 Swell/Consolidation %: 0.0% -1.0% -2.6% -3.6% Results: Settlement Upon Wetting @ Tested By: WS Greer -1.6% 1000 psf: Checked By:K. Runner Swell Pressure (psf): NA

Swell/Consolidation Plot 0.0%

-1.0%

-2.0% Inundated

-3.0% Swell / Consolidation (%) /ConsolidationSwell -4.0% 0.1 1 10 Applied Pressure (ksf) Martinez Associates 14828 West 6th Avenue, Unit 9-B Golden, Colorado 80401 Phone: (303) 459-2216 Fax: (303) 482-2230 Unconfined Compressive Strength of Cohesive Soil (ASTM 2166)

Client Project No.: 518065-000 Proj. Name: Avon WWTF Sampled By: BA Martinez Job No.: 18-0109 Lab Tech: A. Sandoval Test Date: 8/27/18 Sample Date: NP Lab ID Number: 7267 Reviewed By: K. Runner Sample Location: BA-2 C-5 at 22-23' Soil Description: USCS: Unconfined Compressive Strength (q_u): 9,723 psf

Axial Strain (%) Axial Load (lb) Stress-Strain Curve 0.0 0 0.7 1269 10500 1.3 3693 2.0 6286 10000 2.6 8384 9500 3.3 9267 9000 4.0 9723 8500 4.6 8648 8000 5.3 6776 7500 7000 6500

6000 5500 5000

Stress (psf) Stress 4500 4000 3500 3000 2500 2000 1500 1000 500 0 0 1 2 3 4 5 6 Strain % Martinez Associates 14828 West 6th Avenue, Unit 9-B Golden, Colorado 80401 Phone: (303) 459-2216 Fax: (303) 482-2230 Unconfined Compressive Strength of Cohesive Soil (ASTM 2166)

Client Project No.: 518065-000 Proj. Name: Avon WWTF Sampled By: BA Martinez Job No.: 18-0109 Lab Tech: A. Sandoval Test Date: 8/27/18 Sample Date: NP Lab ID Number: 7271 Reviewed By: K. Runner Sample Location: BA-4 C-11 at 40-41' Soil Description: USCS: Unconfined Compressive Strength (q_u): 1,015 psf

Axial Strain (%) Axial Load (lb) Stress-Strain Curve 0.0 0 0.7 29 1500 1.3 577 2.0 940 2.7 1004 3.3 1015 4.0 976 4.6 649 1000

500 Stress (psf) Stress

0 0 1 2 3 4 5

-500

Strain % Martinez Associates 14828 West 6th Avenue, Unit 9-B Golden, Colorado 80401 Phone: (303) 459-2216 Fax: (303) 482-2230 Unconfined Compressive Strength of Cohesive Soil (ASTM 2166)

Client Project No.: 518065-000 Proj. Name: Avon WWTF Sampled By: BA Martinez Job No.: 18-0109 Lab Tech: ASA Test Date: 2/7/19 Sample Date: NP Lab ID Number: 7542 Reviewed By: K. Runner Sample Location: BA-6 at 64-64.4' Soil Description: USCS: Unconfined Compressive Strength (q_u): 903 psf

Axial Strain (%) Axial Load (lb) Stress-Strain Curve 0.0 0 0.6 381 1000 1.3 712 1.9 728 2.6 733 3.2 748 3.9 810 4.5 879 5.2 893 5.8 892 6.5 890 7.1 903 7.8 817 8.4 806 500 Stress (psf) Stress

0 0 1 2 3 4 5 6 7 8 9 Strain % Martinez Associates 14828 West 6th Avenue, Unit 9-B Golden, Colorado 80401 Phone: (303) 459-2216 Fax: (303) 482-2230 Unconfined Compressive Strength of Cohesive Soil (ASTM 2166)

Client Project No.: 518065-000 Proj. Name: Avon WWTF Sampled By: BA Martinez Job No.: 18-0109 Lab Tech: ASA Test Date: 2/7/19 Sample Date: NP Lab ID Number: 7545 Reviewed By: K. Runner Sample Location: BA-8 at 34-34.8' Soil Description: USCS: Unconfined Compressive Strength (q_u): 5,226 psf

Axial Strain (%) Axial Load (lb) Stress-Strain Curve 0.0 0 0.6 1333 6000 1.2 2570 1.9 4069 5500 2.5 4999 3.1 5226 5000 3.7 3716 4.3 2731 4500

4000

3500

3000

Stress (psf) Stress 2500

2000

1500

1000

500

0 0 1 2 3 4 5 Strain %