subsurface exploration report owl canyon road …4396 greenfield drive windsor, colorado 80550 (970)...

SUBSURFACE EXPLORATION REPORT OWL CANYON ROAD (AKA LCR 70) – ROADWAY IMPROVEMENTS

BETWEEN LCR 19 (AKA TAFT HILL ROAD) AND LCR 15 (AKA TERRY LAKE ROAD) LARIMER COUNTY, COLORADO

EEC PROJECT NO. 1172049

Prepared for:

Interwest Consulting Group 1218 West Ash – Suite C Windsor, Colorado 80550

Attn: Mr. Bob Almirall, P. E. ([email protected])

Prepared by:

Earth Engineering Consultants, LLC 4396 Greenfield Drive

Windsor, Colorado 80550

4396 G R E E N F I E L D DR I V E WI N D S O R, C O L O R A D O 8 0 5 5 0

( 9 7 0 ) 5 4 5 - 3 9 0 8 F A X ( 9 7 0 ) 6 6 3 - 0 2 8 2 w w w . e a r t h - e n g i n e e r i n g . c o m

September 25, 2017 Interwest Consulting Group 1218 West Ash – Suite C Windsor, Colorado 80550 Attn: Mr. Bob Almirall, P. E. ([email protected]) Re: Subsurface Exploration Report

Owl Canyon Road (AKA Larimer County Road (LCR) 70 – Roadway Improvements Between LCR 19 (AKA Taft Hill Road) and LCR 15 (AKA Terry Lake Road) Larimer County, Colorado EEC Project No. 1172049

Mr. Almirall: Enclosed, herewith, are results of the geotechnical subsurface exploration and pavement design evaluation completed by Earth Engineering Consultants, LLC personnel for the referenced project. This study was completed in general accordance with our proposal dated May 31, 2017, and generally conforms to Larimer County Urban Area Street Standards (LCUASS) Pavement Design Criteria. For this subsurface exploration, a total of twenty-two (22) soil borings, eighteen (18) pavement related borings and four (4) structural related borings identified as borings, (B-11 & B-12 and B-18 & B-19), were drilled on July 19, and 20, 2017, at selected locations within the extent of the proposed roadway improvements. Eighteen (18) borings were drilled to approximate depths of 10-1/2-feet below existing site grades within the existing roadway alignment, and four (4) deeper foundation related borings, two (2) per culvert structure were drilled to approximate depths of 20 to 30-1/2-feet below site grades. This report provides the pavement design thicknesses for the proposed widening of Owl Canyon Road (LCR 70) for a stretch of approximately 2-miles beginning near Larimer County Road (LCR) 19 (AKA Taft Hill Road) and continuing east toward LCR 15 (AKA Terry Lake Road), and for the two (2) culvert replacement structures along the roadway alignment. The existing pavement wearing surface along this portion of Owl Canyon Road (LCR 70) generally consisted of approximately 1-1/2 to 7 inches of existing asphalt underlain by approximately 4 to 14 inches of existing aggregate base course (ABC). Clayey sand and/or sandy

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 2 lean clay subsoils were encountered beneath the existing pavement and underlying ABC sections and extended to the depths explored at approximately 10-1/2 feet in pavement borings, and/or to the bedrock formation below. Varying amounts of gravel were encountered within in the overburden subsoils. Claystone and/or interbedded sandstone/siltstone/claystone was encountered in all four (4) of the structural borings and pavement borings B-5, B-7, B-9, and B-14 at depths of near surface grades to approximately 15 feet below site grades and extended to the depths explored, approximately 10-1/2 to 30-1/2 feet below existing site grades. The bedrock materials were generally moderately hard to hard and weathered nearer surface; however, became less weathered and more competent with depth. Groundwater was observed in several of the pavement and structural related test borings at approximate depths of 6 to 9-1/2 feet below existing site grades during the drilling operation, within a majority of the borings located on the eastern portion of the roadway alignment. Groundwater levels are identified on the upper right corner of the enclosed borings logs included in the Appendix of this report. All of the borings were backfilled with a non-shrink cementitious grout material as per the Larimer County Engineering Department’s “street-cut” permit upon completion of the drilling exploration; therefore, stabilized groundwater measurements were not obtained. A majority of the in-place soils were found to exhibit low swell potential characteristics and suitable bearing strength characteristics with the exception of two isolated areas. Swell indices for samples tested in the vicinity of borings B-9 and B-20 were exhibited slightly higher results; above the LCUASS maximum allowable value of 2 percent. Therefore, an isolated swell mitigation plan consisting of a minimum 2-foot over excavation and moisture conditioning replacement concept of the in-place subgrade soils would be required in this area. Consideration could also be given to a fly ash treatment/subgrade stabilization approach; recommendations are provided in the text portion of this report. We believe the majority of the widening portions for Owl Canyon Road (LCR 70) could be supported on the in-place native subsoils, or on newly placed and compacted fill material. The proposed widening sections could be constructed as a composite HMA/ABC pavement section placed over an approved/prepared subgrade section consisting of either on-site materials or imported fill material in general compliance with LCUASS pavement design criteria. Results of

SUBSURFACE EXPLORATION REPORT

OWL CANYON ROAD (AKA LCR 70) – ROADWAY IMPROVEMENTS BETWEEN LCR 19 (AKA TAFT HILL ROAD) & LCR 15 (AKA TERRY LAKE ROAD)

LARIMER COUNTY, COLORADO EEC PROJECT NO. 1172049

September 25, 2017

INTRODUCTION The subsurface exploration for the proposed roadway improvements/widening along Owl Canyon road (A.K.A. Larimer County Road (LCR) 70) in Larimer County, Colorado has been completed in general accordance with Larimer County Urban Area Street Standard (LCUASS) Pavement Design Standards. For this subsurface exploration, a total of twenty-two (22) soil borings, eighteen (18) pavement related borings, and four (4) structural related borings (B-11 & B-12 and B-18 & B-19), were drilled on July 19 and 20, 2017, at selected locations within the extent of the proposed roadway improvements. The eighteen (18) pavement borings were drilled to approximate depths of 10-1/2 feet below existing site grades within the existing roadway alignment and the four (4) deeper foundation related borings, two (2) per culvert structure, were drilled to approximate depths of 25 to 30-1/2 feet below site grades. Individual boring logs and a diagram indicating the approximate boring locations are provided with this report. The project, as we understand, will consist of the roadway improvements/widening along Owl Canyon Road (A.K.A. Larimer County Road 70), approximately 2-miles in length, between LCR 19 (AKA Taft Hill Road) and LCR 15 (AKA Terry Lake Road) including two (2) box culvert replacements as indicated herein, in Larimer County, Colorado. Owl Canyon Road is currently a narrow 2-lane arterial roadway. The purpose of this report is to describe the subsurface conditions encountered in the test borings, analysis and evaluate the test data and provide recommendations for subgrade support and pavement sections for the proposed roadway improvements, as well as foundation design criteria for each structure. EXPLORATION AND TESTING PROCEDURES The boring locations were established in the field by EEC personnel by pacing and estimating angles from identifiable site features. The roadway/pavement related borings were spaced approximately 500-lineal feet along the planned roadway widening/improvements and generally positioned as shown on the site plan, staggered between eastbound and westbound lanes. For

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 2 each culvert structure, two (2) borings were drilled on opposite corners. The approximate boring locations are indicated on the attached boring location diagram. The locations of the borings should be considered accurate only to the degree implied by the methods used to make the field measurements. The test borings were performed with a CME-75 drill rig equipped with a hydraulic head employed in drilling and sampling operations. The boreholes were advanced by using 4-inch nominal diameter continuous flight augers. Samples of the subsurface materials encountered were obtained using split-barrel and California barrel sampling procedures in general accordance with ASTM Specifications, D1586 and D3550, respectively. In the split-barrel and California barrel sampling procedures, standard sampling spoons are driven into the ground by means of a 140-pound hammer falling a distance of 30 inches. The number of blows required to advance the samplers is recorded and is used to estimate the in-situ relative density of cohesionless soils and, to a lesser degree of accuracy, the consistency of cohesive materials. All samples obtained in the field were sealed and returned to our laboratory for further examination, classification, and testing. Laboratory moisture content tests were completed on each of the recovered samples. Atterberg limits and washed sieve analysis tests were completed on selected samples to evaluate the percentage and plasticity of fines in the subgrades. Swell/consolidation tests were performed on representative samples to evaluate the soil’s tendency to change volume with variation in moisture content. Composite samples were obtained from borings for Hveem Stabilometer/R-Value (ASTM Specification D2844) testing analyses to determine the in-situ subgrade strength characteristics. Results of the outlined tests are indicated on the attached boring logs and summary sheets. As a part of the testing program, all samples were examined in the laboratory by an engineer and classified in accordance with the attached General Notes and the Unified Soil Classification System, based on the soil’s texture and plasticity. The estimated group symbol for the Unified Soil Classification System is indicated on the boring logs and a brief description of that classification system is included with this report. Classification of the bedrock was based on visual and tactual observation of disturbed samples and auger cuttings. Coring and/or petrographic analysis may reveal other rock types.

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 3 SUBSURFACE CONDITIONS Based on the results of field borings and laboratory testing, subsurface conditions can be generalized as follows. The existing pavement wearing surface along this portion of Owl Canyon Road (LCR 70) generally consisted of approximately 1-1/2 to 7-inches of existing asphalt underlain by approximately 4 to 14-inches of existing aggregate base course (ABC). Clayey sand and/or sandy lean clay subsoils were encountered beneath the pavement and underlying ABC and extended to the depths explored at approximately 10-1/2 feet in pavement borings, and/or to the bedrock formation below. Varying amounts of gravel were encountered in the overburden soils. Claystone and/or interbedded sandstone/siltstone/claystone was encountered in all structural borings and pavement borings B-5, B-7, B-9, and B-14 at approximate depths of 0 to 15-feet below site grades and extended to the depths explored, approximately 10-1/2 to 30-1/2-feet below existing site grades. The bedrock materials were generally moderately hard to hard and weathered nearer surface; however, became less weathered and more competent with depth. The stratification boundaries indicated on the boring logs represent the approximate locations of changes in soil and bedrock types; in-situ, the transition of materials may be gradual and indistinct. In addition, the soil borings show conditions at the test borings locations; variations in subsurface conditions can occur at relatively short distances from the boring locations. GROUNDWATER CONDITIONS Groundwater was observed in several of the pavement and structural related test borings at approximate depths of 6 to 9-1/2-feet below existing site grades during the drilling operation, within a majority of the borings located on the eastern portion of the roadway alignment. All of the borings were backfilled with a non-shrink cementitious grout as per the Larimer County Engineering Department’s “street-cut” permit upon completion of the drilling exploration; therefore, stabilized groundwater measurements were not obtained. Fluctuations in groundwater levels can occur over time depending on variations in hydrologic conditions and other conditions not apparent at the time of this report. Monitoring in cased borings, sealed from the influence of surface infiltration, would be required to more accurately evaluate groundwater levels and fluctuations in the groundwater levels over time.

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 4 Zones of perched and/or trapped groundwater may occur at times in the subsurface soils overlying bedrock, on top of the bedrock surface or within permeable fractures in the bedrock materials. The observations provided in this report represent groundwater conditions at the time of the field exploration, and may not be indicative of other times, or at other locations. ANALYSIS AND RECOMMENDATIONS Swell – Consolidation Test Results The swell-consolidation test is commonly performed to evaluate the swell or collapse potential of soils or bedrock for determining foundation, floor slab, and pavement design recommendations. In this test, relatively undisturbed samples obtained directly from the California barrel sampler are placed in a laboratory apparatus and inundated with water under a predetermined load, generally at 150-psf for pavement analyses, as specified by LCUASS, and typically 500-psf to 1,000 psf for foundation design analyses. All samples are inundated with water and monitored for swell and consolidation. The swell-index is the resulting amount of swell or collapse after inundation, expressed as a percent of the sample’s initial thickness. After the inundation period, additional incremental loads are applied to evaluate the swell pressure and/or consolidation. For this assessment, we conducted eighteen (18) swell-consolidation tests at various intervals/depths throughout the site. The swell index values for the samples analyzed for pavement design criteria, (i.e., soil samples tested at the 150 psf-inundation pressure), revealed generally low swell potential characteristics ranging from approximately (+) 0.0 to (+) 1.9% with one test exhibiting high swell potential characteristics of approximately (+) 6.1% and one exhibiting moderate swell potential characteristics of approximately (+) 2.7%. The swell index values for the samples analyzed for foundation design criteria, (i.e., soil samples evaluated at either 500 or 1,000 psf-inundation pressure), revealed low swell potential characteristics ranging from (+) 0.0 % to (+) 1.9%. The higher swell-index results were of a claystone bedrock sample obtained from boring B-9 and a sandy lean clay sample obtained from boring B-20 respectively at approximate depths of 2-feet below existing site grades and inundation/pre-loaded at 150 psf. A summary of the laboratory swell-consolidation test results is presented on the table below.

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 5

Table I – Laboratory Swell-Consolidation Test Results

Boring No.

Sample No.

Depth, ft.

Material Type

Swell Consolidation Test Results Moisture Content,

%

Dry Density,

PCF

Inundation Pressure,

psf

Swell Index,

% 1 1 2 Clayey Sand (SC) 17.3 112.7 150 (+) 0.5

3 1 2 Clayey Sand (SC) 14.8 120.0 150 (+) 0.0

4 1 2 Sandy Lean Clay (CL) 19.5 104.8 150 (+) 1.9

5 1 2 Clayey Sand (SC) 18.0 109.8 150 (+) 0.0

7 1 2 Silty Sand (SM) 14.6 109.6 150 (+) 0.8


9 1 2 Claystone - Sandy Lean Clay

(CL) 14.0 122.8 150 (+) 6.1

11 3 14 Claystone – Lean Clay (CL) 11.3 127.5 1000 (+) 0.4

12 2 9 Claystone – Lean Clay (CL) 11.0 134.7 500 (+) 1.9

12 4 19 Claystone 9.7 126.9 1000 (+) 0.8




18 1 2 Clayey Sand (SC) 19.7 105.4 150 (+) 1.3

18 5 19 Claystone / Siltstone / Sandstone

– Clayey Sand (SC) 17.2 109 1000 (+) 0.4

19 1 4 Clayey Sand (SC) 14.0 113.9 500 (+) 0.0


22 1 2 Clayey Sand (SC) 16.6 111.2 150 (+) 0.1

Almost all the swell-indexes for the pavement borings, were less than the LCUASS maximum allowable 2% criteria used to determine if a swell-mitigation plan is necessary. Two isolated samples (B-9, S1 and B20, S1) were found to have a swell-indices of 2.7% and 6.1% respectively, both above the maximum allowable value. Based on these results, in our opinion, a swell mitigation plan consisting of either an over excavation of the isolated areas or fly ash treatment of the subgrade is recommended. Colorado Association of Geotechnical Engineers (CAGE) uses the following information presented below in Table II, to provide uniformity in terminology between geotechnical engineers to provide a relative correlation of performance risk to measured swell. “The representative percent swell values are not necessarily measured values; rather, they are a judgment of the swell of the soil and/or bedrock profile likely to influence slab performance.” Geotechnical engineers

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 6 use this information to also evaluate the swell potential risks for foundation performance based on the risk categories.

Table II - Recommended Representative Swell Potential Descriptions and Corresponding

Slab Performance Risk Categories

Slab Performance Risk Category Representative Percent Swell (500 psf Surcharge) Representative Percent Swell

(1000 psf Surcharge)

Low 0 to < 3 0 < 2

Moderate 3 to < 5 2 to < 4 High 5 to < 8 4 to < 6

Very High > 8 > 6

Based on the laboratory test results, the samples analyzed for the two culverts were within the low range. Hveem Stabilometer (R-Value) Composite samples of subgrade materials from the upper 5-feet below pavement grades were obtained from test borings B-1 through B-12 and from borings B-13 through B-22, for laboratory Hveem Stabilometer/R-Value, (ASTM Specification D2844) analyses to determine the subgrade strength characteristics of existing subgrade materials. A summary of the test results is provided below in Table III.

Table III - Summary of Laboratory (R-Value) Characteristics and Classification of Subgrade Soils

Boring Nos. Depth, Ft. Hveem

Stabilometer R-Value

ATTERBERG LIMITS AND CLASSIFICATION LIQUID LIMIT

PLASTIC INDEX

% (-) NO. 200 SIEVE

SOIL DESCRIPTION

B-1 – B-12 0.0 – 5.0 20 29 12 42 Clayey Sand / Sandy Clay

B-13 – B-22 0.0 – 5.0 17 33 19 63

Based on the test results, an R-Value of 17 has been chosen for the pavement design. General Considerations The site appears suitable for the proposed development/construction based on the subsurface conditions; however, certain precautions will be required in the design and construction of roadway

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 7 improvements and new culverts addressing the groundwater conditions in conjunction with the eastern culvert and demolition of the existing concrete structure(s). Based on our understanding of the proposed culvert structures, temporary dewatering will be necessary. Groundwater in the general vicinity of the proposed eastern culvert was encountered at approximate depths of 7-1/2 to 8-1/2-feet below site grades. It is anticipated that excavations for the proposed roadway improvements and the two (2) culvert structures can be accomplished with conventional earthmoving equipment. Excavations penetrating well-cemented sandstone lenses at increased depths, may require the use of specialized heavy-duty equipment such as a rock hammer or core barrel to achieve final design elevations. Consideration should be given to obtaining a unit price for difficult excavation and/or drilling in the contract documents for the project. Shoring mechanisms may be necessary to protect the existing terrain/adjacent slopes in conjunction with both structures during excavation and construction stages. Depending upon the depth of foundation construction for the two (2) structures, a shoring plan may be necessary to protect the adjacent sidewall slopes. The project design team should use the subsurface information provided herein (i.e., subsurface information from borings B-11 and B-12, and B-18 and B-19), to properly design a mechanism for shoring protection. EEC is available to provide supplemental design criteria or details such as but not limited to sheet piles, secant piles or piers, soldier piers, or a tie-back/bracing concept. Demolition of the existing culverts should include complete removal of all concrete/foundation systems within the proposed construction area. This should include removal of any loose backfill found adjacent to existing foundations. All materials derived from the demolition of the existing culverts and associated pavements should be removed and wasted from the site, unless approved for alternative use. Consideration could be given to pulverizing the pavement materials and foundation concrete into 3-inch minus material and devoid of reinforcement, into structural fill material. Additional recommendations for reuse of the existing concrete and pavement materials can be provided upon request. After demolition of the existing structure, a thorough site evaluation should be performed to evaluate and determine the consistency/integrity of the subsoils in the area.


Roadway Subgrade Preparation The subgrade soils are generally low to moderate strength clayey sand or sandy lean clay with varying amounts of gravel, exhibiting relatively low swell potential characteristics. Due to the expansive characteristics of the overburden soil within borings B-9 and B-20, an isolated swell mitigation plan consisting of either an over excavation of the isolated areas or fly ash treatment of the subgrades is recommended. Based on the testing completed, it appears the in-place slightly cohesive clayey sand, and sandy lean clay subgrade soils with swell indexes less than 2% could be used for direct support of the roadways and for roadway subgrade fill provided adequate moisture treatment and compaction procedures are followed. Those procedures would generally include placement in loose lifts not to exceed 9 inches thick and adjustment in moisture content, 2% of optimum moisture content for generally cohesive type soils or 3% for cleaner granular type soils, and compaction to at least 95% of the materials maximum dry density as determined in accordance with ASTM Specification D698, the standard Proctor procedure. If the site clayey sand to silty sand and gravel soils are used as fill material, care will be needed to maintain the recommended moisture content prior to and during construction of overlying improvements. All existing vegetation, and apparent fill materials should be removed from the site improvement areas. To reduce the potential for post-construction movement caused by expansion of the on-site sandy lean clay soils, we recommend sandy lean clay soils in the general area of boring B-9 and B-20 be over excavated and replaced as approved fill material. The over excavation should extend to a depth to allow for at least 2-foot of processed/engineered controlled fill material below final subgrades. The over excavated areas should extend laterally in all directions beyond the edges of the pavements a minimum 8 inches for every 12 inches of over excavated depth. After removal of unacceptable or unsuitable subsoils, removal of over excavation materials, and removal of any previous fill material, and prior to placement of fill and/or site improvements, the exposed soils should be scarified to a depth of 9 inches, adjusted in moisture content to within (+/-) 2% of standard Proctor optimum moisture content for essentially cohesive soils or to a workable moisture content for essentially granular materials and compacted to at least 95% of the material's standard Proctor maximum dry density as determined in accordance with ASTM Specification D698.

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 9 Fill materials used to replace the over excavated zone and establish grades in the pavement/flatwork areas, after the initial zone has been prepared as recommended above, should consist of approved on-site soils or imported structural fill material which is free from organic matter and debris. Approved structural fill materials should be graded similarly to a CDOT Class 5, 6 or 7 aggregate base with sufficient fines to prevent ponding of water within the fill. Structural fill material should be placed in loose lifts not to exceed 9 inches thick, adjusted to a workable moisture content and compacted to at least 95% of standard Proctor maximum dry density as determined by ASTM Specification D698. If selected, a fly ash treatment process would involve incorporating Class C fly ash within the upper 12-inches of the interior roadways subgrade sections from back of curb to back of curb, (in essence the full roadway width), prior to construction of the overlying pavement structure. Stabilization should consist of blending 12% by dry weight of Class C fly ash in the top 12 inches of the subgrades. The blended materials should be adjusted in moisture content to slightly dry of standard Proctor optimum moisture content and compacted to at least 95% of the materials maximum dry density as determined in accordance with the standard Proctor procedure. Compaction of the subgrade should be completed within two hours after initial blending of the Class C fly ash. Proofrolling and recompacting the subgrade section is recommended immediately prior to placement of the aggregate road base section. Soft or weak areas delineated by the proofrolling operations should be undercut or stabilized in-place to achieve the appropriate subgrade support. Moisture conditioning the site subgrade soils could result in pumping subgrade conditions with elevated moisture contents in the subgrades. If pumping is observed, stabilization of the subgrades with the addition of Class C fly ash would be required. Additional recommendations can be provided at time of the proof roll observation. Pavement design methods are intended to provide structural sections with adequate thickness over a particular subgrade such that wheel loads are reduced to a level the subgrade can support. The support characteristics of the subgrade for pavement design do not account for shrink/swell movements of a slightly expansive essentially cohesive subgrade or consolidation of a wetted subgrade. Thus, the pavement may be adequate from a structural standpoint, yet still experience

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 10 cracking and deformation due to shrink/swell related movement of the subgrade. It is therefore important to minimize moisture changes in the subgrade to reduce shrink/swell movements. Care will be needed after preparation of the subgrades to avoid disturbing the subgrade materials. Positive drainage should be developed away from the pavements to avoid wetting of subgrade materials. Subgrade materials becoming wet subsequent to construction of the site improvements can result in unacceptable performance. The collection and diversion of surface drainage away from paved areas is critical to the satisfactory performance of the pavement. Drainage design should provide for the removal of water from paved areas in order to reduce the potential for wetting of the subgrade soils. Long-term pavement performance will be dependent upon several factors, including maintaining subgrade moisture levels and providing for preventive maintenance. The following recommendations should be considered the minimum: The subgrade and the pavement surface should be adequately sloped to promote proper surface

drainage. Install pavement drainage surrounding areas anticipated for frequent wetting (e.g. landscaped

and irrigated islands, etc.), Install joint sealant and seal cracks immediately, Seal all landscaped areas in, or adjacent to pavements to minimize or prevent moisture

migration to subgrade soils; Placing compacted, low permeability backfill against the exterior side of curb and gutter;

and, Placing curb, gutter, and/or sidewalk directly on approved proof rolled subgrade soils without

the use of base course materials. Site grading is generally accomplished early in the construction phase. However, as construction proceeds, the subgrade may be disturbed due to utility excavations, construction traffic, desiccation, or rainfall. As a result, the pavement subgrade may not be suitable for pavement construction and corrective action will be required. The subgrade should be carefully evaluated at the time of pavement construction for signs of disturbance, rutting, or excessive drying. If

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 11 disturbance has occurred, pavement subgrade areas should be reworked, moisture conditioned, and properly compacted to the recommendations in this report immediately prior to paving. Please note that if during or after placement of the stabilization or initial lift of pavement, the area is observed to be yielding under vehicle traffic or construction equipment, it is recommended that EEC be contacted for additional alternative methods of stabilization, or a change in the pavement section.

Site Preparation – On-Site Structures All existing vegetation and/or topsoil should be removed from improvement and/or fill areas in conjunction with the proposed structures. Demolition of the existing concrete culverts should include complete removal of all concrete within the proposed construction areas. This should include removal of any loose backfill found adjacent to any existing feature. All materials derived from the demolition of any existing feature/structure should be removed from the site and not be allowed for use in any on-site fills without approval. Consideration could be given to pulverizing the concrete debris into 3-inch minus material and incorporating into the on-site soils as a mechanism to enhance the structural integrity of the cohesive materials. Additional recommendations can be provided upon request for implementation of this concept. Any fill material and any softer “silted-in” material associated with the existing structures, when demolition, removal and/or construction procedures occur should also be removed from the improvement or fill areas.

Although final site grades were not available at the time of this report, based on our understanding of the proposed development, we anticipate about 1 to 5-feet of cut and fill may be necessary to achieve final design grades along the new roadway alignment(s) and possibly within the proposed structure areas. After stripping and completing all cuts and prior to placement of any fill or site improvements, we recommend the exposed soils be scarified to a minimum depth of 9-inches, adjusted in moisture content to within ±2% of standard Proctor optimum moisture content and compacted to at least 95% of the material's standard Proctor maximum dry density as determined in accordance with ASTM Specification D-698. For stabilization purposes, if necessary, consideration could be given to placement of a granular material, such as a 3-inch minus recycled concrete or equivalent, embedded into the underlying subsoils, prior to placement of additional fill material or operating heavy earth-moving

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 12 equipment. Removal and replacement of a defined depth of the softer soils could also be considered. Supplemental recommendations can be provided upon request based on conditions encountered at the time of construction. Fill soils required for developing the proposed structural related subgrades, after the initial zone has been prepared or stabilized where necessary, should consist of approved, low-volume-change materials, which are free from organic matter and debris. It is our opinion the on-site subsoils could be used as general site fill material, provided adequate moisture treatment and compaction procedures are followed. To minimize the amount of potential movement, we suggest any engineered fill materials consist of essentially granular soils equivalent to a CDOT Class 7 ABC material. We recommend all fill materials be placed in loose lifts not to exceed 9 inches thick and adjusted in moisture content, +/- 2% for cohesive soils and +/- 3% for cohesionless soils, of optimum moisture content and compacted to at least 95% of the materials maximum dry density as determined in accordance with ASTM Specification D698, the standard Proctor procedure. Areas of deeper fills may experience settlement from underlying native soils and within the placed fill materials. Settlement on the order of 1 to 1-1/2-inch per each 10 feet of fill depth could be estimated. The rate of settlement will be dependent on the type of fill material placed, percent of placement density, and construction methods. Granular soils will consolidate essentially immediately upon placement of overlying loads. Cohesive soils will consolidate at a slower rate.

Foundation Systems – General Considerations The site appears suitable for the proposed construction based on the results of our field exploration and our understanding of the proposed development plans. The following foundation systems were evaluated for use on the site for the proposed structures planned as part of the Owl Canyon Road roadway improvements: Conventional Type Spread Footings bearing on the approved native subsoils, approved

engineered fill material extended to the underlying bedrock, and/or on the bedrock formation, and

Grade beams and straight shaft drilled piers/caissons extending into the underlying bedrock,


Spread Footing Foundation System – Two (2) Culvert Crossing Structures

We anticipate the two (2) structures will consist of lightly loaded concrete box culverts, either 3 or 4-sided pre-cast or cast-in-place structures. For these structures, we assume loads will be less than 3 klf, which could be supported by the use of spread footings bearing upon approved native subsoils, engineered fill material extended to the bedrock formation below and/or on or into the underlying bedrock. All footings for each structure should bear on a uniform, consistent strata to minimize the potential for differential movement of dissimilar materials. The native undisturbed subsoils associated with the two (2) structures (i.e., in the vicinity of borings B-11 and B-12, and B-18 and B-19) exhibited low swell potential and moderate bearing characteristics. Care should be taken to remove any soft compressible soils before placement of the footings. In areas where soft compressible subsoils are exposed during the foundation excavation observation, supplemental ground modifications may be necessary to reduce the potential for movement, such as placement of a course granular 3-inch minus pit run type material to enhance the subgrade soils structural integrity and placement of structural fill material. Footings bearing on approved native granular subsoils, ground modified native subsoils or engineered structural fill material could be designed for a maximum net allowable bearing pressure of 2,000 psf. If footings are to be extended to the underlying bedrock formation (i.e., to approximate depths of 7 to 9 feet below site grades in the general vicinity of B-11 and B-12, or 13 to 15-1/2 feet below site grades in the general vicinity of Boring B-18 and B-19), footings could be designed for a maximum net allowable bearing pressure of 4,000 psf. The net bearing pressure refers to the pressure at foundation bearing level in excess of the minimum surrounding overburden pressure. Total load should include full dead and live loads. Structural fill material, if utilized as the foundation bearing stratum, should consist of approved structural fill materials which are free from organic matter and debris. Structural fill consisting of CDOT Class 5, 6 or 7 aggregate base course materials, either natural or recycled concrete could be considered. The fill and backfill soils should be placed in loose lifts not to exceed 9 inches thick and adjusted to a moisture content of +/- 2 % of optimum moisture content, and compacted to at least 95%

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 14 (for backfill portions) and 98%, (beneath all foundations), of standard Proctor maximum dry density per ASTM Specification D-698 or, as appropriate, 65% of relative density. After placement of the fill materials, care should be taken to avoid excessive wetting or drying of those materials. Bearing materials which are loosened or disturbed by the construction activities or materials which become dry and desiccated or wet and softened should be removed and replaced or reworked in place prior to construction of the overlying improvements. Foundation Systems – Drilled Piers/Caissons For the proposed culverts, consideration could also be given to supporting the proposed structures on straight shaft drilled piers/caissons extending into the underlying bedrock formation. Particular attention will be required in the construction of drilled piers due to the presence of groundwater. Bedrock was encountered at approximate depths of 7 to 15-feet below existing site grades in borings B-11 & 12 and B-18 & 19. For axial compression loads, the drilled piers could be designed using a maximum end bearing pressure of 25,000 pounds per square foot (psf), along with a skin-friction of 2,500 psf for the portion of the pier extended into the underlying firm and/or harder bedrock formation. Straight shaft piers should be drilled a minimum of 10-feet into competent or harder bedrock. To satisfy forces in the horizontal direction, piers may be designed for lateral loads using a modulus of 75 tons per cubic foot (tcf) for native granular materials or engineered/structural fill material, and 400 tcf in bedrock for a pier diameter of 12 inches. The coefficient of subgrade reaction for varying pier diameters is as follows:

Table IV: Coefficient of Subgrade Reaction (tons/ft3)

Pier Diameter (inches) Engineered Fill or Granular Soils Bedrock

18 50 267 24 38 200 30 30 160 36 25 133

When the lateral capacity of drilled piers is evaluated by the L-Pile (COM 624) computer program, we recommend that internally generated load-deformation (P-Y) curves be used. The following

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 15 parameters may be used for the design of laterally loaded piers, using the L-Pile (COM 624) computer program:

Table V: L-Pile Design Parameters – Owl Canyon Road Proposed Culverts

Parameters Native Granular Soils or Structural Fill On-Site Slightly

Cohesive Subsoils Bedrock

Unit Weight of Soil (pcf) 130(1) 115(1) 125(1)

Cohesion (psf) 0 200 5000

Angle of Internal Friction () (degrees) 35 25 28

Strain Corresponding to ½ Max. Principal Stress Difference 50

--- 0.02 0.015

*Notes: 1) Reduce by 64 PCF below the water table Drilling caissons to design depth should be possible with conventional heavy-duty single flight power augers equipped with rock teeth on the majority of the site. However, areas of well-cemented sandstone bedrock lenses may be encountered throughout the site at various depths where specialized drilling equipment and/or rock excavating equipment may be required. Excavation penetrating the well-cemented sandstone bedrock may require the use of specialized heavy-duty equipment, together with rock augers and/or core barrels. Consideration should be given to obtaining a unit price for difficult caisson excavation in the contract documents for the project. Due to the depth of groundwater within the proposed eastern culvert alignment, maintaining open shafts should not be expected without stabilizing measures. In borings for the eastern culvert groundwater was encountered at approximate depths of 7-1/2 to 8-1/2-feet below site grades; therefore, we expect temporary casing will be required to adequately/properly drill and clean piers prior to concrete placement. Groundwater should be removed from each pier hole prior to concrete placement. Pier concrete should be placed immediately after completion of drilling and cleaning. A maximum 3-inch depth of groundwater is acceptable in each pier prior to concrete placement. If pier concrete cannot be placed in dry conditions, a tremie should be used for concrete placement.

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 16 Due to potential sloughing and raveling, foundation concrete quantities may exceed calculated geometric volumes. Pier concrete with slump in the range of 6 to 8 inches is recommended. Casing used for pier construction should be withdrawn in a slow continuous manner maintaining a sufficient head of concrete to prevent infiltration of water or the creation of voids in pier concrete. Foundation excavations should be continuously observed by the geotechnical engineer. A representative of the geotechnical engineer should inspect the bearing surface and pier configuration. If the soil conditions encountered differ from those presented in this report, supplemental recommendations may be required.

Lateral Earth Pressures

For any area of the proposed development having below grade construction, such as retaining walls, etc., those portions will be subject to lateral earth pressures. Passive lateral earth pressures may help resist the driving forces for retaining wall or other similar site structures. Active lateral earth pressures could be used for design of structures where some movement of the structure is anticipated, such as retaining walls. The total deflection of structures for design with active earth pressure is estimated to be on the order of one half of one percent of the height of the down slope side of the structure. We recommend at-rest pressures be used for design of structures where rotation of the walls is restrained. Passive pressures and friction between the footing and bearing soils could be used for design of resistance to movement of retaining walls. Coefficient values for backfill with anticipated types of soils for calculation of active, at rest and passive earth pressures are provided in the table below. The assumed friction angles of the soils should be verified at the time of construction and the design modified or alternate materials used if the selected materials do not match the assumed designed values. Equivalent fluid pressure is equal to the coefficient times the appropriate soil unit weight. Those coefficient values are based on horizontal backfill with backfill soils consisting of essentially granular materials with a friction angle of 30 degrees. For the at-rest and active earth pressures, slopes away from the structure would result in reduced driving forces with slopes up away from the structures resulting in greater forces on the walls. The passive resistance would be reduced with slopes away from the wall. The top 30-inches of soil on the passive resistance side of walls could be used as a surcharge load;

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 17 however, should not be used as a part of the passive resistance value. Frictional resistance is equal to the tangent of the friction angle times the normal force.

Table VI: Lateral Earth Pressures

Soil Type Low Plasticity Cohesive Medium Dense Granular

Wet Unit Weight 115 130

Saturated Unit Weight 135 140

Friction Angle () – (assumed) 25° 35°

Active Pressure Coefficient 0.40 0.27

At-rest Pressure Coefficient 0.58 0.43

Passive Pressure Coefficient 2.46 3.70

Surcharge loads or point loads placed in the backfill can also create additional loads on below grade walls. Those situations should be designed on an individual basis. The outlined values do not include factors of safety nor allowances for hydrostatic loads and are based on assumed friction angles, which should be verified after potential material sources have been identified. Care should be taken to develop appropriate drainage systems behind below grade walls to eliminate potential for hydrostatic loads developing on the walls. Those systems would likely include perimeter drain systems extending to sump areas or free outfall where reverse flow cannot occur into the system. Where necessary, appropriate hydrostatic load values should be used for design. Pavement Sections Pavement section design is based on subgrade conditions and anticipated traffic volume. For this study, we conducted two (2) Hveem Stabilometer (R-Value) tests (ASTM Specification D2844), which revealed values of 20 and 17. As previously discussed herein, based on the test results of the sandy lean clay and clayey sands subsoils, for purposes of this report we are analyzing the roadway improvements using an R-Value equivalent to 17. We understand that Owl Canyon road is classified as a 2-lane major arterial roadway with truck traffic and average daily traffic (ADT) information provided to us from Larimer County Engineering Department. Based on the information provided and included in the appendix of this report; a calculated (EDLA) value of

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 18 approximately 635 has been determined in general accordance with LCUASS pavement design criteria and typical CDOT design criteria. For a 20-year design life, the corresponding 18-kip equivalent single axle load (ESAL) for Owl Canyon Road was calculated at 4,635,500. The recommended pavement sections for the proposed roadway improvements along Owl Canyon Road are provided below in Table VII.

TABLE VII – Owl Canyon Road Pavement Sections (1) Design Traffic (20 year ESAL) Resilient Modulus (R=17) Reliability Serviceability Loss (Terminal Service=2.5) Design Structural Number

4,635,500 4478 90% 2.0 5.01

Composite Section: Alternative A – No Fly Ash Hot Bituminous Pavement S-100, PG 64-22 Hot Bituminous Pavement S-100, PG 58-28 Aggregate Base (Class 5 or Class 6) Structural Number - SN

4″ @ 0.44 = 1.76

4-1/2″ @ 0.44 = 1.98 12″ @ 0.11 = 1.32

5.06

Composite Section: Alternative B – Fly Ash Treated Subgrade Hot Bituminous Pavement S-100, PG 64-22 Hot Bituminous Pavement S-100, PG 58-28 Aggregate Base (Class 5 or Class 6) Fly Ash Treated Subgrade (12” section @ 10” of full credit) Structural Number - SN

3″ @ 0.44 = 1.32 4″ @ 0.44 = 1.76 9″ @ 0.11 = 0.99 10″ @ 0.1 = 1.00

5.07

Larimer County typically allows for a pavement thickness reduction concept/credit of 12 inches for use of fly ash treated subgrade using a 10-inch section credit and applying a structural coefficient of either 0.05 or 0.10, depending upon the compressive strength achieved in the laboratory of the blended fly ash treated subgrade material. If in excess of 150 psi is achieved, then a strength coefficient of 0.10 for a 10-inch section could be used in the overall pavement structural number evaluation; otherwise a half-strength credit of 0.05 could be used. The recommended pavement sections assume that full strength will be given. If the subgrade is fly ash treated and found to have a compressive strength less than 150 psi, the pavement sections should increase in thickness.

Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 19 We recommend aggregate base be graded to meet a Class 5 or Class 6 aggregate base. Aggregate base should be adjusted to a workable moisture content and compacted to achieve a minimum of 95% of standard Proctor maximum dry density. The recommended pavement sections are minimums; thus, periodic maintenance should be expected. Longitudinal and transverse joints should be provided as needed in concrete pavements for expansion/contraction and isolation. The location and extent of joints should be based upon the final pavement geometry. Sawed joints should be cut in accordance with ACI recommendations. All joints should be sealed to prevent entry of foreign material and dowelled where necessary for load transfer. Since the site soils have some shrink/swell potential, pavements could crack in the future primarily because of the volume change of the soils when subjected to changes in moisture content of the subgrades. The cracking, while not desirable, does not necessarily constitute structural failure of the pavement.

Water Soluble Sulfates – (SO4) The water-soluble sulfate (SO4) testing of the on-site overburden subsoils indicated sulfate contents ranging from 320 ppm to 740 ppm, while the underlying bedrock formation revealed a sulfate content on the order of approximately 210 ppm to 320 ppm. Test results are summarized in the table below.

TABLE VIII - Water Soluble Sulfate Test Results

Sample Location Description Soluble Sulfate Content (mg/kg) Soluble Sulfate Content (%)

B-2, S-1 at 2’ Sandy Lean Clay (CL) 740 0.07


B-9, S-2 at 4’ Claystone 210 0.02

B-11, S-4 at 14’ Claystone 320 0.03

B-18, S-3 at 9’ Clayey Sand (SC) 320 0.03


Earth Engineering Consultants, LLC EEC Project No. 1172049 September 25, 2017 (Revised from August 22, 2017) Page 20 In general, sulfate contents less than 0.1% water soluble sulfate (SO4) in soils, percent by weight, are considered negligible risk of sulfate attack on Portland cement concrete. Less than 0.1% results would typically indicate that ASTM Type I Portland cement is suitable for all concrete on and below grade. Therefore, based on the results as presented herein it appears Type I Portland cement should be used. Foundation concrete should be designed in accordance with the provisions of the ACI Design Manual, Section 318, Chapter 4. GENERAL COMMENTS The analysis and recommendations presented in this report are based upon the data obtained from the soil borings performed at the indicated locations and from any other information discussed in this report. This report does not reflect any variations, which may occur between borings or across the site. The nature and extent of such variations may not become evident until construction. If variations appear evident, it will be necessary to re-evaluate the recommendations of this report. It is recommended that the geotechnical engineer be retained to review the plans and specifications so that comments can be made regarding the interpretation and implementation of our geotechnical recommendations in the design and specifications. It is further recommended that the geotechnical engineer be retained for testing and observations during earthwork and foundation construction phases to help determine that the design requirements are fulfilled. This report has been prepared for the exclusive use of Interwest Consulting Group, on behalf of Larimer County, for specific application to the project discussed and has been prepared in accordance with generally accepted geotechnical engineering practices. No warranty, express or implied, is made. In the event that any changes in the nature, design, or location of the project as outlined in this report are planned, the conclusions and recommendations contained in this report shall not be considered valid unless the changes are reviewed and the conclusions of this report modified or verified in writing by the geotechnical engineer.

Earth Engineering Consultants, LLC

DRILLING AND EXPLORATION DRILLING & SAMPLING SYMBOLS: SS: Split Spoon ‐ 13/8" I.D., 2" O.D., unless otherwise noted PS: Piston Sample ST: Thin‐Walled Tube ‐ 2" O.D., unless otherwise noted WS: Wash Sample R: Ring Barrel Sampler ‐ 2.42" I.D., 3" O.D. unless otherwise noted PA: Power Auger FT: Fish Tail Bit HA: Hand Auger RB: Rock Bit DB: Diamond Bit = 4", N, B BS: Bulk Sample AS: Auger Sample PM: Pressure Meter HS: Hollow Stem Auger WB: Wash Bore

Standard "N" Penetration: Blows per foot of a 140 pound hammer falling 30 inches on a 2‐inch O.D. split spoon, except where noted.

WATER LEVEL MEASUREMENT SYMBOLS: WL : Water Level WS : While Sampling WCI: Wet Cave in WD : While Drilling DCI: Dry Cave in BCR: Before Casing Removal AB : After Boring ACR: After Casting Removal Water levels indicated on the boring logs are the levels measured in the borings at the time indicated. In pervious soils, the indicated levels may reflect the location of ground water. In low permeability soils, the accurate determination of ground water levels is not possible with only short term observations.

DESCRIPTIVE SOIL CLASSIFICATION Soil Classification is based on the Unified Soil Classification system and the ASTM Designations D‐2488. Coarse Grained Soils have move than 50% of their dry weight retained on a #200 sieve; they are described as: boulders, cobbles, gravel or sand. Fine Grained Soils have less than 50% of their dry weight retained on a #200 sieve; they are described as : clays, if they are plastic, and silts if they are slightly plastic or non‐plastic. Major constituents may be added as modifiers and minor constituents may be added according to the relative proportions based on grain size. In addition to gradation, coarse grained soils are defined on the basis of their relative in‐place density and fine grained soils on the basis of their consistency. Example: Lean clay with sand, trace gravel, stiff (CL); silty sand, trace gravel, medium dense (SM).

CONSISTENCY OF FINE‐GRAINED SOILS Unconfined Compressive Strength, Qu, psf Consistency

Group

Symbol

Group Name

Cu≥4 and 13E GP Poorly-graded gravel F

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

Fines Classify as CL or CH GC Clayey Gravel F,G,H

Cu≥6 and 13E SP Poorly-graded sand I

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

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

inorganic PI>7 and plots on or above "A" Line CL Lean clay K,L,M

PI15% gravel, add "with gravel" to

group name

JIf Atterberg limits plots shaded area, soil is a CL-

ML, Silty clay

Unified Soil Classification System

Soil Classification

Criteria for Assigning Group Symbols and Group Names Using Laboratory Tests

Sands 50% or more

coarse fraction

passes No. 4 sieve

Fine-Grained Soils

50% or more passes

the No. 200 sieve

OWL CANYON IMPROVEMENTS LARIMER, COLORADO

EEC PROJECT NO. 1172039 JULY 2017

1B-1

B-2

B-3

B-4

B-5

B-6

B-7

B-8

B-9

B-10

B-11

B-12

B-13

B-14

B-15

B-16 B-18

B-19

B-20

B-21

B-222

B-17

500'

B-4

B-5

B-6

Boring Location DiagramOwl Canyon Road - Wellington, Colorado

EEC Project Number: 1172049July 2017

EARTH ENGINEERING CONSULTANTS, LLC

B-1-10, 13-17, & 20-22:Approximate Locations for 22Borings Drilled Approximately500 LF Staggered Each Lane,Drilled 10' Deep

Legend

Borings 11-12 & 18-19 Drilled35-50' Deep for BridgeFoundations

1 Site Photos(Photos taken in approximatelocation, in direction of arrow)

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA

SPT HAMMER: AUTOMATIC SOIL DESCRIPTION D N QU MC DD -200

TYPE (FEET) (BLOWS/FT) (PSF) (%) (PCF) LL PI (%) PRESSURE % @ 500 PSF

ASPHALT - 7" _ _

ABC - 9" 1

_ _

CLAYEY SAND (SC) 2

brown / grey / rust _ _ % @ 150 psf

loose to medium dense CS 3 16 3500 17.3 111.8 27 11 49.6 400 psf 0.5%

_ _

4

_ _

brown / red SS 5 20 4500 17.9

with calcareous deposits & trace gravel _ _

6

_ _

7

_ _

8

_ _

9

_ _

SS 10 7 3000 15.2

_ _

BOTTOM OF BORING DEPTH 10.5' 11

_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _


OWL CANYON ROAD (LCR 70) IMPROVEMENTS

LARIMER COUNTY, COLORADO

PROJECT NO: 1172049 LOG OF BORING B-1 JULY 2017SHEET 1 OF 1 WATER DEPTH

START DATE 7/19/2017 WHILE DRILLING None

SURFACE ELEV N/A 24 HOUR N/A

FINISH DATE 7/19/2017 AFTER DRILLING N/A

A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 10" 1

_ _

SANDY LEAN CLAY (CL) 2

brown _ _

stiff to very stiff CS 3 9 3500 18.3 106.0

_ _

4

_ _

with trace gravel SS 5 20 9000+ 17.8

_ _

6

_ _

7

_ _

8

_ _

9

with gravel seams _ _

SS 10 50/10" -- 5.6

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _




LOG OF BORING B-2PROJECT NO: 1172049 JULY 2017SHEET 1 OF 1 WATER DEPTH




A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 10" 1

_ _

CLAYEY SAND (SC) 2

brown _ _ % @ 150 psf

loose to medium dense CS 3 20 3500 14.8 120.8 24 12 32.7

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 3" _ _

ABC - 10" 1

_ _


brown / grey _ _ % @ 150 psf

very stiff CS 3 21 9000+ 19.5 104.7 800 psf 1.9%

with trace gravel _ _

4

_ _

CLAYSTONE SS 5 19 9000+ 14.9

brown / grey / rust _ _

highly weathered 6

_ _

7

_ _

8

_ _

9

_ _

SS 10 50/9" 9000+ 11.7

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 10" 1

_ _

CLAYEY SAND (SC) 2

brown _ _ % @ 150 psf

medium dense CS 3 12 9000+ 18.0 108.5

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 10" 1

_ _


brown / red _ _

very stiff CS 3 8 8000 11.1 111.7


4

_ _

SS 5 7 5000 10.8

_ _

6

_ _

7

_ _

8

_ _

9

_ _

SS 10 21 7000 13.3

_ _

BOTTOM OF BORIN GDEPTH 10.5' 11

_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 1.5" _ _

ABC - 12" 1

_ _

SILTY SAND (SM) - FILL 2

brown / grey / rust _ _ % @ 150 psf

medium dense CS 3 16 6000 14.6 54.6 28 5 17.0 300 psf 0.1%

_ _

4

_ _

SS 5 26 8000 7.3

_ _

6

_ _

7

_ _

8

_ _

CLAYSTONE 9

brown / grey / rust _ _

highly weathered SS 10 19 7000 18.8

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 1.5" _ _

ABC - 9" 1

_ _


brown _ _ % @ 150 psf

very stiff CS 3 17 4000 14.8 115.4 500 psf 0.7%

with gravel _ _

4

_ _

SS 5 18 9000+ 11.6

_ _

6

_ _

7

_ _

8

_ _

9

LEAN CLAY (CL) _ _

grey / olive SS 10 6 4500 12.2

very stiff _ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 6.25" _ _

1

CLAYSTONE _ _

brown / grey / rust 2

highly weathered _ _ % @ 150 psf

CS 3 36 9000+ 14.0 119.3 38 20 69.2 6000 psf 6.1%

_ _

4

_ _

SS 5 41 9000+ 13.8

_ _

6

_ _

7

_ _

8

_ _

9

_ _

SS 10 50 9000+ 14.2

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 7" 1

_ _

SANDY LEAN CLAY (CL) - FILL 2

brown _ _

very stiff CS 3 24 9000+ 10.8 119.1

_ _

4

_ _

SS 5 17 9000 17.3

SANDY LEAN CLAY (CL) _ _

brown / red 6

very stiff _ _

with trace gravel 7

_ _

8

_ _

9

brown _ _

SS 10 8 6500 19.7

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



_ _


brown / red _ _

with trace gravel 2

_ _

3

_ _

4

_ _

CS 5 28 -- 1.3 117.3

_ _

6

_ _

7

_ _

8

CLAYSTONE _ _

brown / grey / rust / olive 9

highly weathered _ _

SS 10 50/11" 9000+ 14.4

_ _

11

_ _

12

_ _

13

_ _

14

_ _ % @ 1000 psf

CS 15 50/7" 9000+ 11.3 125.6 37 21 88.7 1400 psf 0.4%

_ _

16

_ _

17

_ _

18

_ _

19

_ _

SS 20 50/8" 9000+ 10.3

_ _

21

_ _

22

_ _

23

_ _

24

_ _

CS 25 50/6" 9000+ 10.6 119.2

BOTTOM OF BORING DEPTH 25.0' _ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



_ _

CLAYEY SAND (SC) 1

brown / red _ _

dense 2

with gravel _ _

3

_ _

4

_ _

SS 5 28/8" -- 2.0

_ _

6

_ _

7

_ _

8

_ _

9

_ _

CLAYSTONE CS 10 40 9000+ 11.0 125.4 37 22 87.2 2500 psf 1.9%

brown / grey / olive / rust _ _

11

_ _

12

_ _

13

_ _

14

_ _

SS 15 50/9" 9000+ 10.5

_ _

16

_ _

17

_ _

18

_ _

19

_ _ % @ 1000 psf

CS 20 50/6" 9000+ 9.7 123.4 2000 psf 0.8%

_ _

21

_ _

22

_ _

23

_ _

24

_ _

SS 25 50/6" 9000+ 9.8









A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 7" 1

_ _


brown / red _ _ % @ 150 psf

very stiff CS 3 15 8000 16.5 109.6 500 psf 0.8%

_ _

4

_ _

with trace gravel SS 5 3 4000 15.2

_ _

6

_ _

7

_ _

8

_ _

9

SILTY SANDY LEAN CLAY (CL) _ _

brown / red SS 10 2 -- 22.7

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _





START DATE 7/20/2017 WHILE DRILLING 9'



A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 12" 1

_ _


brown / red _ _

very stiff CS 3 13 9000+ 15.1 114.7


4

_ _

SS 5 10 8000 18.2

_ _

6

_ _

7

_ _

8

_ _

SANDSTONE / SILTSTONE / CLAYSTONE 9

brown / grey / olive _ _

SS 10 41/11" 9000+ 15.5

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 9" 1

_ _



very stiff to medium stiff CS 3 18 5000 14.9 114.3 30 17 65.4 1600 1.2%

with traces of gravel _ _

4

_ _

SS 5 4 2000 22.1

_ _

6

_ _

7

_ _

8

_ _

9

SILTY CLAYEY SAND (SM/SC) _ _

red SS 10 6 -- 16.7



_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 1.5" _ _

ABC - 12" 1

_ _


brown _ _

very stiff CS 3 12 5500 18.7 106.3

_ _

4

_ _

SS 5 12 5000 19.5

_ _

6

_ _

7

_ _

CLAYEY SAND with GRAVEL (SC) 8

medium dense _ _

9

_ _

SS 10 27 -- 10.0

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 6" _ _

ABC - 4" 1

_ _


dark brown _ _ % @ 150 psf

very stiff to stiff CS 3 20 9000+ 13.7 119.4 38 23 63.9 2000 psf 0.9%


4

_ _

SS 5 6 2500 21.4

_ _

6

_ _

7

_ _

8

_ _

9

SILTY CLAYEY SAND (SM/SC) _ _

red, medium dense SS 10 14 500 20.5



_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 3" _ _

ABC - 4.5" 1

_ _

CLAYEY SAND (SC) 2


loose to medium dense CS 3 7 7000 19.7 111.9 3500 psf 1.3%

_ _

4

_ _

brown / red SS 5 2 4000 20.1

_ _

6

_ _

7

_ _

8

_ _

9

brown / red _ _

CS 10 11 4000 20.2 107.5

_ _

11

_ _

12

gravel seams _ _

13

_ _

CLAYSTONE / SILTSTONE / SANDSTONE 14

brown / olive / grey / rust _ _

SS 15 33 5000 22.7

_ _

16

_ _

17

_ _

18

_ _

19

_ _ % @ 1000 psf

CS 20 50/10" 9000+ 17.2 125.3 41 21 45.7 2500 psf 0.4%

_ _

21

_ _

22

_ _

23

_ _

24

_ _

SS 25 50/10" 6500 21.6

Continued on Sheet 2 of 2 _ _





START DATE 7/20/2017 WHILE DRILLING 8.5'



A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



Continued from Sheet 1 of 2 26

_ _

CLAYSTONE / SANDSTONE / SILTSTONE 27

brown / olive / grey / rust _ _

28

_ _

29

_ _

CS 30 50/4.5"


31

_ _

32

_ _

33

_ _

34

_ _

35

_ _

36

_ _

37

_ _

38

_ _

39

_ _

40

_ _

41

_ _

42

_ _

43

_ _

44

_ _

45

_ _

46

_ _

47

_ _

48

_ _

49

_ _

50

_ _






7/20/2017 AFTER DRILLING N/A

SURFACE ELEV 24 HOUR N/A

FINISH DATE

A-LIMITS SWELL

N/A

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 5" _ _

ABC - 8" 1

_ _


brown / red _ _

soft 3

_ _

4

_ _

CS 5 7 1000 14.0 114.1

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



Continued from Sheet 1 of 2 26

_ _

CLAYSTONE / SANDSTONE / SILTSTONE 27

brown / grey / olive / rust _ _

28

_ _

29

_ _

SS 30 50/7" 5000 19.9

_ _


_ _

32

_ _

33

_ _

34

_ _

35

_ _

36

_ _

37

_ _

38

_ _

39

_ _

40

_ _

41

_ _

42

_ _

43

_ _

44

_ _

45

_ _

46

_ _

47

_ _

48

_ _

49

_ _

50

_ _






7/20/2017 AFTER DRILLING N/A

SURFACE ELEV 24 HOUR N/A

FINISH DATE

A-LIMITS SWELL

N/A

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 9" 1

_ _


brown _ _ % @ 150 psf

very stiff to medium stiff CS 3 16 9000+ 18.9 103.9 32 18 61.8


4

_ _

brown / tan SS 5 12 5000 20.9

_ _

6

_ _

7

_ _

8

_ _

9

red _ _

SS 10 8 1500 19.2

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 2" _ _

ABC - 14" 1

_ _


dark brown _ _

very stiff to soft CS 3 9 4000 23.2 100.2


4

_ _

SS 5 9 6000 18.6

_ _

6

_ _

7

_ _

8

_ _

9

_ _

SS 10 10 1000 24.3

_ _


_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

DATE:

RIG TYPE: CME55

FOREMAN: DG

AUGER TYPE: 4" CFA



ASPHALT - 3" _ _

ABC - 10" 1

_ _

CLAYEY SAND (SC) 2

brown _ _ % @ 150 psf

very loose to loose CS 3 8 5000 16.6 110.7 200 psf 0.1%


4

_ _

brown / red SS 5 3 500 13.6

_ _

6

_ _

7

_ _

8

_ _

9

CLAYEY SAND (SC) _ _

red, medium dense SS 10 11 -- 15.2



_ _

12

_ _

13

_ _

14

_ _

15

_ _

16

_ _

17

_ _

18

_ _

19

_ _

20

_ _

21

_ _

22

_ _

23

_ _

24

_ _

25

_ _








A-LIMITS SWELL

Project:Location:Project #:Date:

Owl Canyon Road (LCR 70) ImprovementsLarimer County, Colorado1172049July 2017

Beginning Moisture: 17.3% Dry Density: 112.7 pcf Ending Moisture: 15.4%Swell Pressure: 400 psf % Swell @ 150: 0.5%

Sample Location: Boring 1, Sample 1, Depth 2'Liquid Limit: 27 Plasticity Index: 11 % Passing #200: 49.6%

SWELL / CONSOLIDATION TEST RESULTS

Material Description: Brown / Grey / Rust Clayey Sand (SC)

-10.0

-8.0

-6.0

-4.0

-2.0

0.0

2.0

4.0

6.0

8.0

10.0

0.01 0.1 1 10

Perc

ent M

ovem

ent

Load (TSF)

Sw

ell

Con

solid

atio

Water Added


Owl Canyon Road (LCR 70) ImprovementsLarimer County, Colorado1172049July 2017

Beginning Moisture: 14.8% Dry Density: 120 pcf Ending Moisture: 15.0%Swell Pressure:


SWELL / CONSOLIDATION TEST RESULTS

Material Description: Brown / Grey Sandy Lean Clay (CL)Sample Location: Boring 4, Sample 1, Depth 2'Liquid Limit: - - Plasticity Index: - - % Passing #200: - -Beginning Moisture: 19.5% Dry Density: 104

subsurface exploration report owl canyon road …4396 greenfield drive windsor, colorado 80550 (970)...

Documents