Geotech Rport

Office Locations

ALASKA Anchorage Juneau Fairbanks Ketchikan Kodiak Palmer GEOTECHNICAL REPORT CITY OF MONTROSE ARIZONA SOUTH HILLCREST EXTENSION Tempe Tucson E. NIAGARA TO E. OAK GROVE MONTROSE, COLORADO COLORADO Denver Montrose Grand Junction

MONTANA Billings Bozeman Butte Great Falls Helena Miles City March 10, 2017 NORTH DAKOTA Dickinson

OREGON Bend Portland

WASHINGTON Redmond Seattle

WYOMING Gillette Lander Laramie

Sheridan

Prepared for:

Scott Murphy City of Montrose 433 South 1st Street Montrose, CO 81401

TABLE OF CONTENTS 1.0 Introduction ...... 1 2.0 Construction Plans ...... 1 3.0 Site Conditions ...... 1 4.0 Geologic Setting ...... 3 5.0 Geologic Hazards ...... 3 5.1 Runoff & Erosion ...... 3 5.2 Flooding ...... 3 5.3 Shallow Groundwater ...... 4 5.4 Expansive and Compressible Soil ...... 5 6.0 Soil Characteristics ...... 5 6.1 Field Evaluation ...... 5 6.2 Laboratory testing ...... 6 7.0 Pavement Design ...... 7 7.1 Traffic Analysis ...... 7 7.2 Equivalent Single Axle Loading (ESAL) Calculation ...... 8 7.3 Soil Sample Classification ...... 8 7.4 Subgrade Support Characteristics ...... 8 7.5 Road Section Selection ...... 10 8.0 Recommendations ...... 11 8.1 General Design Criteria ...... 11 8.2 Site Preparation and Grading ...... 11 8.3 Concrete ...... 12 8.4 Pavement Section ...... 13 8.5 Concrete Flatwork ...... 13 8.6 Excavation and Shoring ...... 13 9.0 Closing Considerations ...... 15 9.1 Standard of Care and Interpretation of Subsurface Data ...... 15 9.2 Use of This Report ...... 15 9.3 Retention of Samples ...... 16 10.0 Additional Services ...... 16 APPENDIX A - Project Maps ...... A APPENDIX B – Test Pit Logs ...... B APPENDIX C - Laboratory Results ...... C

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page i

1.0 INTRODUCTION

DOWL conducted an evaluation of shallow subsurface and site conditions on February 1, 2017 along the general alignment of the southerly extension of Hillcrest Drive from E. Niagara Road to E. Oak Grove Road (hereafter referred to as the “Hillcrest Extension”) for the City of Montrose to provide an evaluation and design of a roadway. The evaluation consisted of a site reconnaissance, excavating five test pits, logging and testing of materials found, and analysis of available data. This report presents the findings of our evaluation and our geotechnical engineering recommendations for site preparation, management of drainage, and pavement design.

2.0 CONSTRUCTION PLANS

The proposed Hillcrest Extension will be roughly 2,800 feet long (0.5 miles) and will be designed and constructed in accordance with the City’s Standards and Specifications (May 2012), the American Association of State Highway and Transportation Official’s Geometric Design of Highways and Streets (2011), and the Federal Highway Administration’s Manual on Uniform Traffic Control Devices (2012). For the “northern reach” portion of the alignment (e.g. north of the undeveloped agricultural fields where a road already exists), the City has requested four (4) alternatives to be presented in the 30% design phase of this project that include (1.) leave as-is; (2.) limited pedestrian improvements (i.e., 8-foot wide sidewalks); (3.) addition of bike lanes; and (4.) full corridor re-build (i.e., City’s 80-foot wide template). The “southern reach” will use an 80-foot template (back of walk to back of walk) containing a center turn lane, two through lanes, detached sidewalks, curb, gutter and bike lanes on each side of the road. The roadway will be designed with a design speed of 40 mph unless approved otherwise.

3.0 SITE CONDITIONS

The Hillcrest Extension is located in the southeast portion of the City of Montrose, east of Highway 550 (South Townsend St), between E. Niagara Road and E. Oak Grove Road, as seen on the Vicinity Map (Map 1, Appendix A). The Site Plan (Map 2, Appendix A) is a Google Earth image with the approximate locations of the test pits indicated. The following photographs were taken of the site on January 25, 2017 to show the general site conditions.

Photo 1. View south along the existing Hillcrest Drive which accesses the Sunrise Creek development. The white painted line at the bottom of the image is located at the stop sign for the intersection with E. Niagara Road.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 1 of 16

Photo 2. View south along the east side of the bridge that crosses the Montrose Arroyo. Note the three drain pipes that allow water to drain under the primitive dirt road. A house is located to the left of the wall on the left side of the photograph.

Photo 3. View south from the northern end of the irrigated field near the middle of the project area. Note the manhole for the stormwater drain system that extends south to E. Oak Grove Road. Note the linear depression in the field where snow is collecting, which is caused by settlement of the fill over the stormwater line.

Photo 4. View north from the southern end of the general alignment, immediately north of E. Oak Grove Road. An irrigated field is to the left (west) and an undeveloped and unirrigated parcel of land is located to the right of the fence seen in the upper right portion of the photograph.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 2 of 16

According to the USGS Montrose East topographic quadrangle, the site is at an average elevation of 5,860 feet. As seen in the above photographs, the terrain is generally flat-lying with a very gentle slope (<2%) down to the northwest. The Montrose Arroyo flows to the northwest across the northern portion of the project area, as seen on the Site Plan (Map 2). The southern two-thirds of the alignment contains irrigated agricultural fields and undeveloped land, while the northern one-third contains the existing Hillcrest Drive, residences, and a bridge that crosses the Montrose Arroyo.

4.0 GEOLOGIC SETTING

According to the Geologic Map of the Montrose East Quadrangle (CGS Open-File Report 07-02 by Noe et al, 2007), the Hillcrest Extension is located on Quaternary alluvial mudflow (Qamf) deposits. These are fine-grained alluvial slopewash deposits that eroded off of the outcrops of Mancos Shale (“Adobes”) located at the valley margin to the east. These soils are extensive valley fill deposits found east of the Uncompahgre River throughout the Montrose area. They are typically composed of clay, silt and fine sand, with variable amounts of salts such as gypsum and calcite. When saturated, they are typically weak and compressible (hydro- compactive) and when dry or moist they can be moderately expansive. Underlying this valley fill is Mancos Shale at variable depths. The Mancos Shale formation, is a marine calcareous shale that ranges from mudstone and claystone to harder shale and siltstone with occasional layers of fine sandstone and limestone. This formation underlies the entire Uncompahgre Valley and the upper layers of this formation are generally soft, brittle, and highly weathered, becoming less weathered with depth.

5.0 GEOLOGIC HAZARDS

Based on our field study, available references and knowledge of the area, we have assessed the relevant geologic hazards to the proposed roadway.

5.1 Runoff & Erosion

Surface runoff from rainfall and snowmelt drains as sheetflow across the proposed roadway alignment towards the Montrose Arroyo and within the furrows and ditches of the irrigated land. The overland flow can cause erosion, especially in the vicinity of this drainage, as water is concentrated in this area. However, erosion is likely minimal in the irrigated fields due to the vegetative cover of the hay grasses and the low gradient of the terrain. The native fine-grained soils are prone to erosion, so protection of the soils during construction such as with the use of silt fences and rip rap are important wherever water will be concentrated during runoff.

5.2 Flooding

The Federal Emergency Management Agency (FEMA) has performed a flood elevation study of the Montrose Arroyo and the results are provided online at the Flood Map Service Center (www.msc.fema.gov/portal). A subset of the base flood elevation survey is shown below (Figure 1) as it relates to the project area. FEMA has mapped the 100-year floodplain as Zone AE, which means that base flood elevations have been determined for this level of flood event,

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 3 of 16 and it is shown in blue on the map below. Anticipated base flood elevations are shown in black at various locations along the stream channel.

Figure 1. This is an excerpt from the FEMA FIRM (Flood Insurance Rate Map) Panel 0778D for the Montrose Arroyo in the vicinity of the Hillcrest Extension Project. Note the elevations of the 100-year flood event in black numbers and the extent of flooding shown in blue lines and dots.

Due to the potential flooding of Montrose Arroyo, protection of the banks of the drainage in the vicinity of the bridge will be important in the re-design of the road crossing. Additionally, flood protection can be provided through a grading plan designed to accommodate the anticipated flood levels.

5.3 Shallow Groundwater

During our field investigation in early February, we did not encounter groundwater in any of the five test pits that were excavated to depths of 6 to 9 feet below existing grade. However, this is the dry time of the year and it is anticipated that groundwater will be present below the roadway during the late spring through early fall irrigation season, when fields in the region are flood irrigated. The test pits in the southern two-thirds of the project area, which are within an irrigated field or adjacent to one, were soft with high moisture contents that increased with depth. We installed groundwater monitoring standpipes in TP#1, TP#2 and TP#5 to monitor groundwater during the late spring and summer. A set of groundwater readings were made on March 6, 2017, and north piezometer (TP#1) was dry, the middle piezometer (TP#2) was moist, and the south piezometer (TP#5) had a water level at 7.45 feet.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 4 of 16

Shallow groundwater can be problematic as it weakens soils and can cause pumping during construction and potential road failure in the long-term if not properly mitigated. Specific recommendations for soil preparation, grading and site drainage are given below in the Recommendations Section of this report.

5.4 Expansive and Compressible Soil

Soil materials containing some types of clay, especially bentonite (montmorillonite), can expand in volume with water absorption and then shrink upon drying. These expansive soils cause serious damage to foundations, roadways, pavements, and embankments. Compressible soils are generally soils that have been laid down rapidly, have a weak matrix containing voids, and/or are not naturally in a dense or compacted state. Compressible soils typically have a large proportion of fine-grained materials, especially silt. Clayey soils can also be compressible if they are saturated when loads are applied.

The potential hazard from expansive and compressible soil materials is the differential movement of soils from swell pressure and potential collapse. This hazard can be partly reduced by managing on-site drainage so that water accumulation, ponding or penetration into the soil in the vicinity of roadways is reduced to as great a degree as practical. Additionally, problematic soil can be over-excavated and replaced with structural fill and/or geotextiles and geogrids can be used to improve soil strength. These methods are discussed in further detail below in the Recommendations Section.

6.0 SOIL CHARACTERISTICS

6.1 Field Evaluation

Five test pits were excavated along the general roadway alignment using a backhoe and operator supplied by the City. Test Pit #1 (TP#1) is located at the north end and TP#2 to TP#5 extend to the south, as shown on the Site Plan (Map 2, Appendix A). The soil and groundwater conditions were logged and representative soil samples were obtained and tested in our laboratory. The subsurface conditions found in the test pits are shown on the attached Test Pit Logs (Appendix B) and laboratory results are provided in Appendix C.

The soil conditions in the five test pits were similar, with minor variations. Generally, there is around 0.3 to 1-foot of organics, grass roots and clay loam soil that indicates a plow layer in some of the test pits. Below this is a silty clay to clayey silt to 2 to 3 feet with some loose and weathered shale fragments in some of the pits. Where drier, this soil strata is stiff, but where more moist, it is soft to very soft and easy to excavate with the backhoe. Below the 2 to 3 foot depth, the soils to 6 to 9 feet are silty clay to clay with gray and orange mottling in TP#2-TP#5. These are redoximorphic features that indicate a fluctuating water table, causing alternating oxidation and reduction of the iron and manganese within the soil. The northern test pit (TP#1) is the only “dry” test pit and it does not have mottling, which suggests it is not influenced by regional flood irrigation. All other test pits become wetter and softer with depth, but no groundwater was observed in any of the test pits in our early February field testing. The following photographs illustrate the native soil conditions during our field testing.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 5 of 16

Left photograph (Photo 5) is a view to the north as TP#2 was being excavated and the right photograph (Photo 6) shows the fine-grained, wet nature of the soil at this site.

Left photograph (Photo 7) is a view to the north at TP#5 while it was about 4 feet deep and the right photograph (Photo 8) shows the gray/orange mottling of soil from around 3 feet deep in TP#4.

As indicated on the test pit logs, the pits were terminated at depths of 6 to 9 feet and slotted PVC standpipes were placed in TP#1, TP#2 and TP#5 during the backfilling process for groundwater monitoring during the irrigation season. All pits were backfilled and compacted using the backhoe.

6.2 Laboratory testing

Laboratory tests were performed on the predominant native soil types such as plasticity (Atterberg Limits), particle size characteristics, moisture-density relationship (Proctor), strength (California Bearing Ratio – CBR), and corrosivity potential (Appendix C). Atterberg limits tests were performed on bulk samples collected in TP#1, TP#3 and TP#5 at depths of 1.5 to 4 feet.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 6 of 16

The three samples have liquid limits (LL) of 30 to 50, plastic limits (PL) of 17 to 19, and plasticity indices (PI) of 13, 21 and 31. A soil with a PI of less than 15 is considered to have a low potential for swelling when wetted and shrinking when dried, a soil with a PI of between 15 and 30 is considered to have moderate potential for swelling or shrinking, and soil with a PI over 30 can be expected to have a high probability of changing volume with changes in moisture content. As seen from these results, the soils range from low to moderately high plasticity. Gradation analyses (hydrometers) performed on these three samples indicate that the soils are composed of 0% gravel, 0.4 to 6% sand, 21 to 59% silt, and 34 to 79% clay. Based on these laboratory test results, these soils classify as lean clay (CL) to fat clay (CH) according to the Unified Soil Classification System (USCS).

Soil strength and moisture-density (Standard Proctor) tests were performed on a bulk sample obtained from a depth of 2 to 4 feet in TP#5. The Standard Proctor was 108.0 pcf at 17.1% moisture content. The California Bearing Ratio (CBR) test result was 1.9 at a 95% Maximum Dry Density (MDD) of 102.6 pcf.

A series of geochemical tests were conducted on bulk soil sample GS5, taken from a depth of 2 to 4 feet in TP#5. The soil sample had a water soluble sulfate concentration of 1.2%, a chlorides content of 0.012%, an electro-conductivity of 385 µS/cm, and a pH of 7.4. The water soluble sulfates content is indicative of corrosive soil. Recommendations for addressing the corrosive nature of the soil are presented in the Recommendations Section of this report.

In summary, the field observations and laboratory testing indicate that the soils to the depths explored have low to moderately high plasticity, are dominated by fine-grained material (silt and clay) with relatively low density, are weak (very low CBR), and are dry to wet in a natural, mid-winter state. The soils are anticipated to be wetter with a possible shallow groundwater table during the irrigation season. Management of runoff and groundwater will be essential to the long-term performance of the roadway foundation soils.

7.0 PAVEMENT DESIGN

The existing S. Hillcrest Drive from E. Niagara Road to Sunrise Drive is paved with hot mix asphalt (HMA), but the remainder of the alignment is not. The existing pavement structural section is unknown.

7.1 Traffic Analysis

2016 Traffic counts from the Hillcrest Drive Traffic Study by Calibre Engineering were used to design for a 20-year flexible pavement life. Projecting the AM peak hour vehicle count of 196 vehicles that turned west from southbound Hillcrest onto Niagara and assuming they would use southbound Hillcrest to Oak Grove Road, we calculated the 20-year 18-kip Equivalent Single Axle Loads (ESAL’s) for the South Hillcrest Drive section between E. Niagara Road and E. Oak Grove Road as follows:

Assuming 2% annual growth, the 2036 design year ADT is: 196 x Growth factor Tr, where Tr = (1+.02)20 = 1.49

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 7 of 16

Therefore, the 2031 design year ADT = 292 vehicles

7.2 Equivalent Single Axle Loading (ESAL) Calculation

Of the 292 design year vehicles, we estimated that there would be:

80% Passenger cars and pickup trucks x 292 = 234 10% Single Unit Trucks x 292 = 29 10% Multi-axle Unit Trucks x 292= 29

Each of these classification totals were multiplied by the appropriate Colorado Equivalency Factor for flexible pavement from CDOT Table C-1. Those results are:

234 passenger car/pickup truck ADT x 0.003 = 0.702 29 single unit trucks x 0.249 = 6.786 29 multi-axle trucks x 1.087 = 31.523

The total of these three classifications is 0.702+6.786+31.523 = 39.011, which was then multiplied by 365 days per year and by 20 years to get the total number of 18-kip ESAL’s for design.

That total is: 39.011 x 365 x 20 = 284,780 ESAL’s.

Since there will be only one lane in each direction, we reduced the design ESAL’s by multiplying by a lane reduction factor of 0.6. This resulted in a total ESAL count of 170,868. That figure was rounded up to 500,000 ESAL’s to be conservative since the road is classified as an urban collector road.

7.3 Soil Sample Classification

Individual laboratory testing results on representative soil samples obtained from the test pits are attached (Appendices B and C). As discussed above in Sections 6.1 and 6.2 of this report, a California Bearing Ratio (CBR) was determined to be 1.9 for the dominant silty clay (CL) found at this site. This value was used to calculate the Resilient Modulus (MR) of the site soils. Equation 3-1 from the CAPA Guideline for the Design and Use of Asphalt Pavements for Colorado Roadways states:

MR (psi) = 1500 x CBR, so the average MR = 1500 x 1.9 = 2,850 psi

Table 1 below shows the Structural Number (SN) calculations given the MR above.

7.4 Subgrade Support Characteristics

Table 1 below summarizes the typical subgrade support characteristics for the soils encountered. Assumptions for choosing the subgrade characteristics listed in Table 1 are:

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 8 of 16

(a) The pavement structures on site will be exposed to moisture levels approaching saturation more than 25% of the time and that these areas of potential saturation will be have a “good” quality of drainage. No typical drainage information was available for the soils encountered on the site at the time of this report, therefore a CDOT recommended drainage coefficient of m1 = 1.0 was used.

(b) From CDOT’s Table 5.6 Drainage Quality (2014 Edition), it was assumed that water would be removed from all pavement structures within one day and so an overall drainage quality of “good” was used.

(c) A reliability factor of 75% was assumed due to the conservative ESAL count in Section (1) above. CDOT’s Table 1.3 – Reliability (Risk) recommends a range of reliability of 50-85 % for roads. However, 75% reliability was used to represent an acceptable long-term service life.

(d) A standard normal deviate (ZR) of -0.674 and a standard deviation of 0.44, as required by CDOT for all designs, was used.

(e) Per CDOT recommendations, initial and terminal Serviceability Indexes were assumed to be 4.5 and 2.5 respectively, thus a Design Serviceability Loss (ΔPSI) of 2.0 was calculated by subtracting the terminal serviceability index from the initial serviceability index.

Table 1. Pavement Thickness Design Factors Parameter Subgrade Resilient Modulus (psi) 2,850 Drainage coefficient 1.0 Reliability (%) 75

Standard Normal Deviate (ZR) -0.674 Standard Deviation 0.44 Serviceability Loss 2.0 Strength coefficients: HMA 0.44 ABC 0.12 SOIL-CEMENT 0.13 SUBGRADE 0.10

CDOT Equation 3.2 was used to calculate the required pavement section for flexible (asphalt) pavement.

Equation 3.2 states:

SN = a1D1 + a2D2m2 + a3D3m3

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 9 of 16

Where:

a1, a2, a3 = structural layer coefficients D1 = thickness of bituminous surface course (inches) D2 = thickness of base course (inches) D3 = thickness of sub base (inches) m2 = drainage coefficient of base course m3 = drainage coefficient of sub base

The minimum recommended structural number (SN) was calculated to be = 3.89.

7.5 Road Section Selection

Based on the design criteria and calculations presented above, we identified two options for the structural section for the project roadway, as shown in Table 2. Alternative #1 matches the existing roadway structural section on East Oak Grove and is the City’s preferred section. Alternative #2 provides the minimum structural section to meet the structural number of 3.89 identified in our analysis above and is not recommended.

Table 2. Pavement Section Alternatives Class 1 Sub- Pavement HMA Class 6 Base base Course Total Section Section SN Thickness Course Thickness (ABC) Thickness Alternatives (in.) (in.) Thickness (in.) (in.)

Alternative #1 5.08 5 12 12 29*

Alternative #2 3.94 5 6 9 20

*Includes installation of TenCate Mirafi RS280i geosynthetic at the base of the structural section between native subgrade and sub-base course.

Pavement design recommendations are presented in the Recommendations section of this report.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 10 of 16

8.0 RECOMMENDATIONS

Based upon our limited site evaluation and results of our subsurface testing the following recommendations are offered to enhance the long-term performance of the soils and site improvements. It should be noted that the measures offered address only the construction of the Hillcrest Extension. They cannot and will not arrest or prevent large-scale geologic processes that may be on-going within the Montrose area.

8.1 General Design Criteria

1. The management of erosion associated with flooding of the Montrose Arroyo will need to be considered, both during construction and for the life of the project.

2. If a different alignment crossing Montrose Arroyo is desired than is existing, a site- specific geotechnical study should be performed for an alternate bridge site.

3. A groundwater study should be initiated when regional irrigation begins in the spring and should be carried through mid-summer to provide information as to the location of the water table during the growing season.

8.2 Site Preparation and Grading

1. The drainage plan and grading plans should ensure that precipitation, snowmelt, and runoff are conveyed around the roadway. Care should be taken to not concentrate runoff in the vicinity of the Montrose Arroyo and bridge crossing, as these soils are susceptible to erosion.

2. Development should utilize "best practices" for design and construction so that on-site erosion is minimized. This may include selective thinning of vegetation, construction of temporary diversion ditches, silt fencing, and/or dust suppression. The local building official will be able to provide specific details regarding these requirements.

3. Backfill placed in utility trenches should be densely compacted in accordance with project specifications to inhibit surface water infiltration and migration, as well as minimize post-construction settlement of the trench backfill. We recommend low- permeability check-dams be installed in the trenches to inhibit water flow along any utility trenches.

4. Fill used at this site should meet the gradational and compaction requirements listed in Tables 3 and 4 below. Fill should be placed and compacted in maximum 6-inch lifts. Structural fill should not be placed on frozen or wet existing soil or fill material. It is recommended that the excavation be open a minimal amount of time to avoid degradation of the foundation soils.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 11 of 16

Table 3. Gradation Requirements for Fill Material

Type Sieve %Passing, by weight Structural Fill (CDOT Class 6 roadbase) 3/4” (19.0 mm) 100 #4 (4.75 mm) 30-65 #8 (2.36 mm) 25-55 #200 (0.075 mm) 3-12

Structural Fill (CDOT Class 1) 2.5” (63.5 mm) 100 2” (50 mm) 95-100 #4 (4.75 mm) 30-65 #200 (0.075 mm) 3-15

Fill under sidewalks 3” (75 mm) 100 #200 (0.075 mm) 0-5

Free-draining fill 3” (75 mm) 100 ¾” (19 mm) 20-90 #4 (4.75 mm) 0-20 #200 (0.075 mm) 0-3 Note: The Plasticity Index for all fill soils should be less than 6.

Table 4. Compaction Requirements for Fill Material Compaction Application Proctor Moisture Requirement Under sidewalks 90% max. dry density Modified ±2% of optimum Road Subgrade 95% max. dry density Standard 0-4% above optimum Road Subbase 95% max. dry density Modified ±2% of optimum Road base course 95% max. dry density Modified ±2% of optimum Utility Trenches Per project specifications* General landscaping Per project specifications* *As specified by the design engineer on project documents or in accordance with local municipal requirements.

5. Any soils containing organics, debris, topsoil, frozen soil, snow, ice, and other deleterious materials shall not be used for anything other than landscaping.

6. A representative of DOWL should be called out to the site to observe placement of structural fill and verify the compacted density. The City should contact DOWL in advance of the excavations to discuss the specific testing requirements, budget, and scheduling needed for these services.

8.3 Concrete

A water-soluble sulfate test conducted on a representative soil sample in TP#5 (sample GS5) showed sulfate concentrations of 1.2%. This is considered by CDOT to be a Class 2 severity of sulfate exposure. Therefore, we recommend that the cementitious material requirements for Class 2 sulfate exposure in Section 601.04 of the latest edition of the CDOT Specifications for Road and Bridge Construction be consulted and followed.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 12 of 16

8.4 Pavement Section

The following recommendations are offered for pavement section at this site.

1. To provide a stable base for construction of the recommended pavement sections presented above, we recommend that the upper 12 inches of the existing native subgrade soil be scarified and re-compacted to 95% of Standard Proctor (AASHTO T-99) maximum density, at 0 to 4% of optimum moisture content. We then recommend the installation of TenCate Mirafi RS280i geosynthetic on top of the prepared subgrade.

2. Based on material and construction costs and overall section thickness, we recommend that Alternative #1: 12 inches of CDOT Class 2 aggregate sub-base course (ABC) compacted to 95% of Modified Proctor maximum density (AASHTO T-180), followed by 12 inches of CDOT Class 6 and 5 inches of hot mix asphalt (HMA) be used for the new pavement section. The Class 6 ABC should also be compacted to a minimum of 95% of a Modified Proctor maximum density (AASHTO T-180) at +/- 2% of optimum moisture content.

3. Design and construction of the roadway should promote drainage away from the paved areas. Where needed, roadside ditches should either be constructed or modified to accept road drainage.

4. All paving construction activities should be monitored and tested by a competent civil/geotechnical engineering firm for compliance with the recommendations contained in this report and with the specifications in the latest edition of the Montrose County Standards and Specifications for Roads and Bridges.

8.5 Concrete Flatwork

1. Flatwork (sidewalks) should be placed on 6 inches of CDOT Class 6 roadbase over TenCate Mirafi RS280i geosynthetic that is placed on proof-compacted native soil with any topsoil and organic material removed. If additional fill is needed, it should consist of washed rock or structural fill (see Tables 3 and 4), placed and compacted in accordance with project specifications. As previously discussed, flatwork and other improvements supported on the lightly compacted backfill will likely settle over time.

2. All concrete used at this site in contact with native soil should comply with the recommendations in the Concrete Section of these recommendations.

8.6 Excavation and Shoring

1. Temporary excavations should be in accordance with Occupational Safety and Health Administration (OSHA) regulations and with worker safety in mind.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 13 of 16

2. Based upon our evaluation, the silty clay (CL) and clay (CH) found in our test pits would be most nearly represented by an OSHA Type A soil. Our assessment is based upon the soil and groundwater conditions found in our limited evaluation and sampling. The contractor’s “competent person” (defined by OSHA as “an individual capable of identifying existing and predictable hazards…and who has the authorization to take prompt corrective measures to eliminate or manage these hazards and conditions) should evaluate the soil materials exposed during excavation based on composition, structure, and environmental conditions per 29 CFR 1926 and recommend appropriate slope laybacks or shoring, as required. Refer to OSHA’s Technical Manual Section V: Chapter 2 on Excavations: Hazard Recognition in Trenching and Shoring (available online at: www.osha.gov) for further excavation guidelines. We can provide these services, as requested.

3. If the excavations will be made or remain open during wet weather, it is recommended that polyethylene sheeting be secured over the excavation face to minimize sediment runoff and deterioration of the foundation soils. Surface runoff above the cuts should be directed away from the excavation using berms or diversion ditches. Water should not be allowed to accumulate and/or pond anywhere upon the soils in the construction area. It must be removed by gravity or pumped to avoid this condition until permanent drainage systems are operational.

4. Excavation dewatering may be required if the excavation is made during the irrigation season. If groundwater is not mitigated and controlled, oversaturation and soil pumping will occur, making it difficult to achieve a stable subgrade.

5. We anticipate that the excavation of the site soils can be accomplished by conventional excavating equipment.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 14 of 16

9.0 CLOSING CONSIDERATIONS

9.1 Standard of Care and Interpretation of Subsurface Data

This report has been prepared in a manner consistent with local standards of professional geotechnical engineering practice. As previously noted, we did not perform an evaluation of deep subsurface conditions. Evaluation of environmental contaminants was not part of our scope of services performed at this site. The classification of soils and interpretation of subsurface conditions is based on our training and years of experience, but is necessarily based on limited subsurface observation and testing. As such, inferred ground conditions cannot be guaranteed to be exact. No other warranty, express or implied, is made.

Observations of the roadway excavation(s) subgrade by DOWL prior to placing of fabric or fill material are integral parts of these recommendations. If subsurface conditions differing from those described herein are discovered during excavation, construction should be stopped until the situation has been assessed by a representative of DOWL. Construction should be resumed only when remedies or design adjustments, as necessary, have been prescribed.

9.2 Use of This Report

This report is intended for use by the design team specifically to address the site and subsurface conditions as they relate to the proposed structure(s) described in the Construction Plans Section. Changes to the site or proposed development plans may alter or invalidate the recommendations contained herein.

DOWL retains an ownership and property interest in this report. Consistent with the industry, copies of this document that may be relied upon by the design team are limited to those that are signed and sealed by the Geotechnical Engineer (Standard Form of Agreement Between Owner and Geotechnical Engineer for Professional Services, Engineer’s Joint Contract Documents Committee, 1996).

This report, together with ancillary data, analyses, test results, and other components and/or supporting parts are not intended or represented to be suitable for reuse by the design team or others on extensions to this project or on any other project. Any such reuse or modification invalidates all aspects of the report and excuses the Geotechnical Engineer for all responsibility and liability or legal exposure.

This report is considered valid for a period of two years from the date of issue provided the site conditions and development plans have not changed from what is referenced in this report. Changes to the site may occur due to development or natural processes. Additionally, technological advances made in construction and changes in legislation may alter the recommendations made herein. Depending upon the site and proposed development changes, DOWL may require additional evaluation (at additional cost) to update the recommendations contained herein.

City of Montrose South Hillcrest Extension geotech report.docx Project #7122.74681.01 Page 15 of 16

APPENDIX A - PROJECT MAPS

VICINITY MAP Hillcrest Dr

Niagara Rd

Map source: Google Earth

LB LB City of Montrose South Hillcrest Extension 1 02/01/17 Montrose, Colorado 2 7122.74681.01 SITE PLAN

Niagara Rd TP#1

TP#2

TP#3

TP#4

TP#5

Map source: Google Earth (scale unknown)

= approximate Test Pit location

LB LB City of Montrose South Hillcrest Extension 2 02/01/17 Montrose, Colorado 2 7122.74681.01

APPENDIX B – TEST PIT LOGS

NOTES: NOTES: SURFACE ELEVATION: end at of N. corridor LOCATION: TEST PIT with SE corner Niagara E. Rd. 12 11 10 9 8 7 6 5 4 3 2 1 0 DEPTH (ft.) TEST PIT OF LOG

1 Water Level 5 GRAPHIC

PROJECT # PROJECT FIELD DATE DRAFTING STAFF STAFF FIELD SAMPLE TYPE GS1 BS1 BS1 SAMPLE NUMBER light brown, dry, stiff, silty CLAY to clayey SILT (2-7') SILT clayey to stiff, dry, light silty brown, CLAY (1-2') chips shale weathered some CLAY, silty (smears), stiff dry, brown, dry,brown, blocky, clay loam, possible (0.3-1') plow layer brown, dry, CLAY loam with organics and grass roots (0-0.3') No groundwater or bedrock 7' to @7'; installed piezometer excavation of end 7122.74681.01 2/1/2017 TEST LOGPIT - TEST #1PIT (TP#1) LJB LJB SUBSURFACE DESCRIPTION SUBSURFACE South Hillcrest Extension Montrose, Colorado Montrose, City of Montrose Montrose of City EQUIPMENT: backhoe EQUIPMENT: Steve OPERATOR: COMPANY: City of MontroseEXCAVATION

silt=59.3% clay=34.4% gravel=0.0% sand=6.3% PL=17LL=30 PI=13 @1.5-3.5' (CL)GS1 FIELD AND LABORATORY TEST RESULTS NOTES: irrigated field irrigated NOTES: SURFACE ELEVATION: end of N. irrigated LOCATION: TEST PIT field 12 11 10 9 8 7 6 5 4 3 2 1 0 DEPTH (ft.) TEST PIT OF LOG

2 Water Level 5 GRAPHIC

PROJECT # PROJECT FIELD DATE DRAFTING STAFF STAFF FIELD SAMPLE TYPE GS2 DS1 SAMPLE NUMBER wetter with depth with wetter (2.2-9') salts and chips shale some and mottling with SILT clayey to soft, silty CLAY very softmoist to light to wet, brown, to brown moist,brown, soft, (0.4-2.2') silty CLAY brown, moist, soft, silty loamCLAY with organics and grass roots (0-0.4') No groundwater or bedrock 9' to @9'; installed piezometer excavation of end 7122.74681.01 2/1/2017 TEST LOGPIT - TEST #2PIT (TP#2) LJB LJB SUBSURFACE DESCRIPTION SUBSURFACE South Hillcrest Extension Montrose, Colorado Montrose, City of Montrose Montrose of City EQUIPMENT: backhoe EQUIPMENT: Steve OPERATOR: COMPANY: City of MontroseEXCAVATION

FIELD AND LABORATORY TEST RESULTS NOTES: irrigated field irrigated NOTES: SURFACE ELEVATION: S. end LOCATION: TESTof PIT irrigated field 12 11 10 9 8 7 6 5 4 3 2 1 0 DEPTH (ft.) TEST PIT OF LOG

3 Water Level 5 GRAPHIC

PROJECT # PROJECT FIELD DATE DRAFTING STAFF STAFF FIELD SAMPLE TYPE GS3 SAMPLE NUMBER No groundwater or bedrock end of excavation @6' mottling (4-6') gray/orange moist,with brown, stiff, silty CLAY moist,brown, (2.5-4') with some stiff v. SILT CLAY moist,brown, stiff, (0.3-2.5') silty CLAY dk moist,brown, soft, loam with grasssilty CLAY (0-0.3')roots 7122.74681.01 2/1/2017 TEST LOGPIT - TEST #3PIT (TP#3) LJB LJB SUBSURFACE DESCRIPTION SUBSURFACE South Hillcrest Extension Montrose, Colorado Montrose, City of Montrose Montrose of City EQUIPMENT: backhoe EQUIPMENT: Steve OPERATOR: COMPANY: City of MontroseEXCAVATION

gravel=0.0% sand=0.4% PL=19LL=50 PI=31 @2.5-3.5' (CH) GS3 silt=20.7% clay=78.9% FIELD AND LABORATORY TEST RESULTS NOTES: irrigated field to west, non-irrigated east to irrigated field west, to NOTES: SURFACE ELEVATION: Central LOCATION: TEST PIT portion of "double fence" area 12 11 10 9 8 7 6 5 4 3 2 1 0 DEPTH (ft.) TEST PIT OF LOG

4 Water Level 5 GRAPHIC

PROJECT # PROJECT FIELD DATE DRAFTING STAFF STAFF FIELD SAMPLE TYPE GS4 DS2 SAMPLE NUMBER No groundwater or bedrock end of excavation @6' below 2'; becoming softer with depth, but no groundwater mottling orange and gray with SILT clayey moist,to brown, stiff, silty CLAY @1-2'; <22-3 tsftsf Penetrometer below 2' <1" thick organic (0-1') base, at organics with layer plow possible CLAY; silty blocky, moist, brown, 7122.74681.01 2/1/2017 TEST LOGPIT - TEST #4PIT (TP#4) LJB LJB SUBSURFACE DESCRIPTION SUBSURFACE South Hillcrest Extension Montrose, Colorado Montrose, City of Montrose Montrose of City EQUIPMENT: backhoe EQUIPMENT: Steve OPERATOR: COMPANY: City of MontroseEXCAVATION

FIELD AND LABORATORY TEST RESULTS NOTES: irrigated field to west, non-irrigated east to irrigated field west, to NOTES: SURFACE ELEVATION: TEST PIT LOCATION: S. end of "double fence" area near E. Oak Grove Rd. 12 11 10 9 8 7 6 5 4 3 2 1 0 DEPTH (ft.) TEST PIT OF LOG

5 Water Level 5 GRAPHIC

PROJECT # PROJECT FIELD DATE DRAFTING STAFF STAFF FIELD SAMPLE TYPE GS5 BS2 BS2 SAMPLE NUMBER salts (2-9') mottling and gray/orange with SILT clayey moist,to brown, stiff, silty CLAY moist,brown, stiff, (1-2') silty CLAY (0-1') base at organics <1" roots; grass loam; organicspossible moist, and with brown, soft, silty CLAY plow layer No groundwater or bedrock 9' to @9'; installed piezometer excavation of end 7122.74681.01 2/1/2017 TEST LOGPIT - TEST #5PIT (TP#5) LJB LJB SUBSURFACE DESCRIPTION SUBSURFACE South Hillcrest Extension Montrose, Colorado Montrose, City of Montrose Montrose of City EQUIPMENT: backhoe EQUIPMENT: Steve OPERATOR: COMPANY: City of MontroseEXCAVATION

Electro-conductivity=385 µS/cm µS/cm Electro-conductivity=385 chlorides=0.012% pH=7.4 soluble sulfates=1.2%water Std Proctor=108.0pcf @17.1% MC silt=37.3% clay=62.1% gravel=0.0% sand=0.6% PL=17LL=38 PI=21 CBR=1.9 @2-4' (CL) GS5/BS2 FIELD AND LABORATORY TEST RESULTS NOTES: SURFACE ELEVATION: LOCATION: TEST PIT 12 11 10 9 8 7 6 5 4 3 2 1 0 DEPTH (ft.) Test Pit Log

of WATER LEVEL

GRAPHIC Project # Project Date Field Staff Field Drafting Staff Drafting SAMPLE TYPE HARD BEDROCK HARD SANDSTONE SHALE GRAVEL SAND SILT CLAY TOPSOIL FILL GS1 DS1 SAMPLE NUMBER location of free subsurface water subsurface of free location sample bulk sample drive (2-4') (CL) gravel with CLAY sandy to stiff, firm moist, gray, dark RQD = Rock Quality Deisgnation Rock = RQD no structure soil, Residual = W6 Completely weathered = W5 weathered Highly = W4 weathered Moderately = W3 weathered Slightly = W2 Fresh = W1 sand with gravel clayey or gravel clayey = GC sand with gravel silty or gravel silty = GM with gravel poorly-graded or gravel poorly-graded = GP sand with gravel well-graded or gravel well-graded = GW gravel with sand to clayey sand clayey = SC gravel with sand to silty sand silty = SM gravel with sand poorly-graded or sand poorly-graded = SP gravel with sand well-graded or sand well-graded SW = silt elasticity high to sandy/gravelly silt elasticity high = MH plasticity high to sandy/gravelly clay plasticity high = CH silt to sandy/gravelly silt = ML clay lean to sandy/gravelly clay lean = CL Rock Weathering Classification Weathering Rock D-2487) (ASTM System Soil Classification Unified SUBSURFACE DESCRIPTION SUBSURFACE

Unified Soil Classification Soil Classification Unified (see definitions below) definitions (see TEST PIT LOG KEY LOG PIT TEST range in depth of soil unit of soil in depth range Test Pit Log Key EQUIPMENT: EQUIPMENT: OPERATOR: COMPANY:EXCAVATION R6 = Extremely strong rock, >36000 psi R5 = Very strong rock, 14500 - 36000 psi R4 = Strong Rock, 7250 - 14500 psi R3 = Medium strong rock, 3625 - 7250 psi R2 = Weak rock, 725 - 3625 psi R1 = Very weak rock, 150 - 725 psi R0 = Extremely weak rock, 35 - 150 psi Intact Rock Strength Classification SP: swelling pressure swelling SP: Ratio Bearing California CBR: resistance Penetration P: resistance Shear Sh: % silt/clay, Fines: % fraction, sand SF: % fraction, gravel GF: index plasticity PI: limit plastic PL: limit liquid LL: % content, moisture MC: pcf density, dry DD: results: test and performed tests indicate column in this Notes psi: pounds per square inch square per pounds psi: foot cubic per pounds pcf: foot square per pounds psf: strength compressive unconfined UCS: movement total TM: FIELD AND LABORATORY TEST RESULTS FIELD SOIL IDENTIFICATION TERMS

Relative Density of Cohesionless Soils

Description Field Identification N Value

Very Loose Easily penetrated with hand shovel 0-4

Easily penetrated with 1/2" rebar pushed by hand; Loose 4-10 easily excavated with hand shovel

Easily penetrated with 1/2" rebar driven with 5 lb. hammer; Moderately Dense 10-30 difficult to excavate with hand shovel

Penetrated 1 ft. with driven rebar; must be loosened Dense 30-50 with pick to excavate

Penetrated only a few inches with driven rebar; very Very Dense >50 difficult to excavate even with pick

Consistency & Relative Density of Cohesive Soils

Undrained Shear N Value Description Field Identification Strength (psf) (Approx.)

Very Soft Extrudes between fingers when squeezed <250 0-2

Soft Molded by light finger pressure 250-500 2-4

Firm Molded by strong finger pressure 500-1,000 4-8

Stiff Indented by thumb 1,000-2,000 8-15

Very Stiff Indented by thumbnail 2,000-4,000 15-30

Hard Difficult to indent with thumbnail >4,000 >30

Soil Constituents

Modifier trace little some -ey or -y and

% (by weight) 0 - 5 5 - 12 12 - 20 20 - 30 >30

Sheet Field Staff

Drafting Staff Field Soil Identification Terms 1 Field Date of 1 Project #

APPENDIX C - LABORATORY RESULTS

Results are for the exclusive use of the client and apply only to the samples tested and are not indicative of apparently identical samples.

Sample Number: Sample Number: Location: PERCENT FINER 0.0013 mm. 0.0013 mm. 0.0030 mm. 0.0061 mm. 0.0085 mm. 0.0118 mm. 0.0197 mm. 0.0299 %+3" 0.0 pnn ecn Spec. Percent Opening 100 #200 ieFnr(ecn)(X=Fail) (Percent) Finer Size #40 #10 10 20 30 40 50 60 70 80 90 * #4 0 (no specification provided) specification (no 100 Test Results (ASTM D422ASTM(ASTMResultsC117) Test&

TP#1 3 in.

Coarse 2 in. 0.0 100.0 GS1

24.4 29.9 37.3 43.3 49.3 59.2 69.2 93.7 99.7 99.9 1½ in. %Gravel 1 in. ¾ in.

Depth: Depth: ½ in. Fine 10 0.0 Particle Size Distribution Report 3/8 in. 1.5-3.5' * #4 Coarse 0.1 Pass?

#10 Project No: Project: Client: Medium 0.2 1 %Sand GRAIN SIZEGRAIN mm. - #20 City of Montrose of City

Date Received:Date #30 D D CLAY lean brown light D (D 2487)= USCS PL= Hillcrest & Niagara to E. Oak Grove Oak E. to Niagara & Hillcrest Extension Hillcrest 10 50 90 Checked By: #40 = = = Tested By:Tested 7122.74681.01 17 0.0123 0.0635 #60 Fine 6.0 Title:

Atterberg Limits (ASTM D 4318) (ASTM Limits Atterberg #100 0.1 SJ 2/1/17 #140 CL Material Description C D D u 30 85

LL= #200 = Classification = = Coefficients 0.0031 0.0523 Remarks 30 AASHTO(M 145)= Date Tested: Date 59.3 Silt Date Sampled:Date 0.01 %Fines D C D 15 c 60 PI= = = = 0.0204 13 2/9/17 . A-6(11) 2/1/17 34.4 Clay 0.001 Results are for the exclusive use of the client and apply only to the samples tested and are not indicative of apparently identical samples.

Sample Number: Sample Number: Location: PERCENT FINER 0.0012 mm. 0.0012 mm. 0.0027 mm. 0.0052 mm. 0.0073 mm. 0.0101 mm. 0.0170 mm. 0.0262 %+3" 0.0 pnn ecn Spec. Percent Opening 100 #200 ieFnr(ecn)(X=Fail) (Percent) Finer Size #40 #10 10 20 30 40 50 60 70 80 90 * 0 (no specification provided) specification (no 100 Test Results (ASTM D422ASTM(ASTMResultsC117) Test&

TP#3 3 in.

Coarse 2 in. 0.0 100.0 100.0 GS3

46.6 65.1 79.6 83.6 87.6 92.7 97.7 99.6 1½ in. %Gravel 1 in. ¾ in.

Depth: Depth: ½ in. Fine 10 0.0 Particle Size Distribution Report 3/8 in. 2.5-3.5' * #4 Coarse 0.0 Pass?

#10 Project No: Project: Client: Medium 0.0 1 %Sand GRAIN SIZEGRAIN mm. - #20 City of Montrose of City

Date Received:Date #30 D D CLAY FAT brown D (D 2487)= USCS PL= Hillcrest & Niagara to E. Oak Grove Oak E. to Niagara & Hillcrest Extension Hillcrest 10 50 90 Checked By: #40 = = = Tested By:Tested 7122.74681.01 19 0.0014 0.0129 #60 Fine 0.4 Title:

Atterberg Limits (ASTM D 4318) (ASTM Limits Atterberg #100 0.1 SJ 2/1/17 #140 CH Material Description C D D u 30 85

LL= #200 = Classification = = Coefficients 0.0081 Remarks 50 AASHTO(M 145)= Date Tested: Date 20.7 Silt Date Sampled:Date 0.01 %Fines D C D 15 c 60 PI= = = = 0.0022 31 2/9/17 . A-7-6(34) 2/1/17 78.9 Clay 0.001 Results are for the exclusive use of the client and apply only to the samples tested and are not indicative of apparently identical samples.

Sample Number: Sample Number: Location: PERCENT FINER 0.0012 mm. 0.0012 mm. 0.0029 mm. 0.0056 mm. 0.0077 mm. 0.0106 mm. 0.0173 mm. 0.0265 %+3" 0.0 pnn ecn Spec. Percent Opening 100 #200 ieFnr(ecn)(X=Fail) (Percent) Finer Size #40 #10 10 20 30 40 50 60 70 80 90 * 0 (no specification provided) specification (no 100 Test Results (ASTM D422ASTM(ASTMResultsC117) Test&

TP#5 3 in.

Coarse 2 in. 0.0 100.0 GS5

37.6 50.1 64.6 71.6 77.6 89.6 95.6 99.4 99.8 1½ in. %Gravel 1 in. ¾ in.

Depth: Depth: ½ in. Fine 10 0.0 Particle Size Distribution Report 3/8 in. 2-4' * #4 Coarse 0.0 Pass?

#10 Project No: Project: Client: Medium 0.2 1 %Sand GRAIN SIZEGRAIN mm. - #20 City of Montrose of City

Atterberg Limits (ASTM D 4318) (ASTM Limits Atterberg #100 0.1 SJ 2/1/17 #140 CL Material Description C D D u 30 85

LL= #200 = Classification = = Coefficients 0.0142 Remarks 38 AASHTO(M 145)= Date Tested: Date 37.3 Silt Date Sampled:Date 0.01 %Fines D C D 15 c 60 PI= = = = 0.0046 21 2/9/17 . A-6(21) 2/1/17 62.1 Clay 0.001 970-249-6828 ■ 800-865-9847 (fax) ■ 222 South Park ■ Montrose, Colorado 81401 ■ www.dowl.com Alaska ■ Arizona ■ Colorado ■ Montana ■ North Dakota ■ Oregon ■ Washington ■ Wyoming

California Bearing Ratio ASTM D1883

Project Name Hillcrest Extension Date 2/17/17 Project Location Hillcrest & Niagara to E. Oak Grove Project # 7122.74681.01 Client City of Montrose Sample by LB Sample Location TP#5 @2-4' Test by SJ Sample # BS2 Soil Description light brown lean CLAY

CBR @0.1 inch penetration: 0.3 Test dry density: 90.4 pcf CBR @0.2 inch penetration: 0.3 Test moisture content before soaking: 17.3% Average moisture content after soaking: 25.0% Target moisture content: 17.1% Top 1-inch moisture content after soaking: 30.7% Surcharge weight: 10.0 lbs Swell: 1.1%

10 BLOWS

California Bearing Ratio

10.0

9.0

8.0

7.0

6.0

5.0 CBR @ 0.2" = 4.9/1500 X 100 =0.3

4.0 Unit Load (psi) 3.0 CBR @ 0.1" = 2.7/1000 X 100 =0.3 2.0

1.0

0.0 * * * *off-set applied 0.000 0.100 0.200 0.300 0.400 0.500 0.600 Penetration (inch) 970-249-6828 ■ 800-865-9847 (fax) ■ 222 South Park ■ Montrose, Colorado 81401 ■ www.dowl.com Alaska ■ Arizona ■ Colorado ■ Montana ■ North Dakota ■ Oregon ■ Washington ■ Wyoming

California Bearing Ratio ASTM D1883

CBR @0.1 inch penetration: 2.2 Test dry density: 104.1 pcf CBR @0.2 inch penetration: 2.2 Test moisture content before soaking: 17.6% Average moisture content after soaking: 19.7% Target moisture content: 17.1% Top 1-inch moisture content after soaking: 24.5% Surcharge weight: 10.0 lbs Swell: 1.3%

25 BLOWS

California Bearing Ratio

60.0

50.0

40.0

CBR @ 0.2" = 32.3/1500 X 100 =2.2 30.0

CBR @ 0.1" = 21.8/1000 X 100 =2.2 Unit Load (psi) 20.0

10.0

0.0 0.000 0.100 0.200 0.300 0.400 0.500 0.600 Penetration (inch) 970-249-6828 ■ 800-865-9847 (fax) ■ 222 South Park ■ Montrose, Colorado 81401 ■ www.dowl.com Alaska ■ Arizona ■ Colorado ■ Montana ■ North Dakota ■ Oregon ■ Washington ■ Wyoming

California Bearing Ratio ASTM D1883

CBR @0.1 inch penetration: 2.8 Test dry density: 108.3 pcf CBR @0.2 inch penetration: 3.4 Test moisture content before soaking: 17.0% Average moisture content after soaking: 18.3% Target moisture content: 17.1% Top 1-inch moisture content after soaking: 22.6% Surcharge weight: 10.0 lbs Swell: 1.2%

56 BLOWS

California Bearing Ratio

100.0

90.0

80.0

70.0

60.0

50.0 CBR @ 0.2" = 51.0/1500 X 100 =3.4

40.0 Unit Load (psi) 30.0 CBR @ 0.1" = 28.0/1000 X 100 =2.8

20.0

10.0

*off-set applied 0.0 * * * 0.000 0.100 0.200 0.300 0.400 0.500 0.600 Penetration (inch) 970-249-6828 ■ 800-865-9847 (fax) ■ 222 South Park ■ Montrose, Colorado 81401 ■ www.dowl.com Alaska ■ Arizona ■ Colorado ■ Montana ■ North Dakota ■ Oregon ■ Washington ■ Wyoming

California Bearing Ratio ASTM D1883

CBR vs Molded Dry Density

4.0

3 layers @56 blows per 3.5 layer = 100.3% MDD

3.0

2.5 3 layers @25 blows per layer = 96.4% MDD

2.0 CBR

1.5

1.0

3 layers @10 blows per 0.5 layer = 83.7% MDD 95% MDD = 102.6 pcf 0.0 80.0 100.0 120.0 Molded Dry Density (pcf)

MDD = Maximum Dry Density TestedBy: Results are for the exclusive use of the client and apply only to the samples tested and are not indicative of apparently identical samples. Optimum =17.1% moisture =108.0pcf dry density Maximum Project: Project No. Project Hillcrest & Niagara to E. Oak Grove Oak E. Hillcrest&Niagarato specification: Test

Depth Dry density, pcf Location: Location: Elev/ 2-4' 104 105 106 107 108 109 11 HillcrestExtension SJ TP#5 7122.74681.01 City of Montrose of City 7122.74681.01 USCS ASTM D 698-12 Method A Standard A Method 698-12 D ASTM Sample Number: Number: Sample 13 Client: Classification MOISTURE-DENSITYRELATIONSHIP TEST RESULTS TEST BS2 AHOMoist. AASHTO 15 Water content, % content, Water 17.1%, 108.0 pcf 108.0 17.1%, Nat. 17 pG LPI LL Sp.G. 2.70 19 Remarks: MATERIALDESCRIPTION light brown lean CLAY lean brown light 21 %< %> 4No.200 #4 . 23 2.70 = Sp.G. for ZAV 970-249-6828 ■ 800-865-9847 (fax) ■ 222 South Park ■ Montrose, Colorado 81401 ■ www.dowl.com Alaska ■ Arizona ■ Colorado ■ Montana ■ North Dakota ■ Oregon ■ Washington ■ Wyoming

Corrosivity Series

Project Name Hillcrest Extension Date Sampled 2/1/2017 Project Location Hillcrest & Niagara to E. Oak Grove Sampled By LB Project # 7122.74681.01 Date Received 3/1/2017 Client City of Montrose Tests For LB Source/Depth TP#5 @2-4' Sample # GS5 Date Tested 2/15/2017 Soil Description light brown lean CLAY Tested By SJ

Water-soluble sulfates, dry soil basis 1.2 % CDOT CP-L 2103 - Method B

Chlorides 0.012 % CDOT CP-L 2104 - Method B

pH 7.4 ASTM G51

Electroconductivity 385 µS/cm Based on Hach Methods