Attach6 Appendix A-Geotech Report.pdf

Kumar & Associates, Inc. ®

TABLE OF CONTENTS

SUMMARY

PURPOSE AND SCOPE OF STUDY

PROPOSED CONSTRUCTION

SITE CONDITIONS

SUBSURFACE CONDITIONS

ENGINEERING CONSIDERATIONS

SHALLOW FOUNDATIONS

FLOOR SLABS

WATER SOLUABLE SULFATES

SEISMIC DESIGN CRITERIA

SURFACE DRAINAGE

SITE GRADING

PAVEMENT DESIGN

WATER QUALITY POND

EXCAVATION CONSIDERATIONS

DESIGN AND SUPPORT SERVICES

LIMITATIONS

FIG. 1 - LOCATIONS OF EXPLORATORY BORINGS

FIG. 2 - LOGS OF EXPLORATORY BORINGS

FIG. 3 – LEGEND AND NOTES

FIGS. 4 AND 5 - GRADATION TEST RESULTS

TABLE I - SUMMARY OF LABORATORY TEST RESULTS

SUMMARY

1. Below asphalt, concrete, or topsoil, the subsurface profile generally consisted of poorly graded alluvial gravel with silt and sand overlying very hard ash-flow tuff bedrock extending to the maximum explored depths of 5 to 20 feet. Fill was found extending to a depth of 3 feet in Boring 2, and appeared to consist of reworked onsite gravels.

2. Groundwater was not encountered in the borings at the time of our exploration.

3. We recommend the proposed addition be constructed on shallow foundations bearing on bedrock or compacted structural fill. Shallow foundations constructed on the bedrock encountered can be designed for a maximum allowable pressured of 5,000 psf.

Foundations constructed on compacted structural can be designed for a maximum allowable pressured of 3,500 psf.

4. Two test holes were hand dug to expose the existing foundation in an attempt to determine the existing foundation type. A footing was exposed at an approximate depth of 3 feet at the north excavation, but no footing was exposed on the south excavation.

Based on the subsurface conditions encountered, we expect that the existing foundations are shallow.

5. We have assumed an EDLA of 5 for parking stalls, and 10 for drive areas. Based on the subsurface conditions encountered and the estimated traffic volumes, we recommend the pavement section alternatives presented in the following table.

Pavement Section Thickness (in.)

Full Depth

Asphalt Composite Asphalt over Base Course

Portland Cement Concrete over Base

Course Areas Restricted to

Automobiles (i.e. parking stalls)

5 4 over 6 6 over 4

Areas with Automobiles and Occasional Trucks

(i.e. drive lanes)

5.5 4.5 over 6 6 over 4

6. Percolation tests were performed in the area of Boring 4 in the alluvial gravels. A modified percolation test procedure was conducted whereby the infiltration rate is determined by applying a reduction factor to the measured percolation rate to account for the exfiltration occurring through the sides of the percolation hole. Using this method, a relatively high infiltration rate of about 6 inches per hour was obtained.

Because the bedrock is relatively impervious, a discounted infiltration rate should be used if the proposed pond will be near the bedrock interface.

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PURPOSE AND SCOPE OF STUDY

This report presents the results of a geotechnical engineering study for the proposed improvements to the existing Del Norte Senior High School to accommodate its new use as a

Forest Service Office. The project site is shown on Fig. 1. The study was conducted in accordance with our Proposal No. C19-188.R, dated May 20, 2019, to provide recommendations for foundations and pavement section thickness, and to provide infiltration rates to aid in the design of a water quality pond.

This report has been prepared to summarize the data obtained during this study, and to present our conclusions and recommendations based on the proposed construction and the subsurface conditions encountered. Design parameters and a discussion of geotechnical engineering considerations related to the proposed construction are included in the report.

PROPOSED CONSTRUCTION

We understand the project will include the renovation of a portion of the existing school building to accommodate an interior space of about 14,400 SF to be used for the Forest Service, which may include a small single-story addition. New parking and drive areas, as well as a new water quality pond will also be constructed. The exact layout of the addition is not known at this time, but it is anticipated within the courtyard area at the front of the school near Boring 1. The water quality pond is proposed to be located at or near the existing solar array, which is to be removed. This area is near Boring 4.

We anticipate that structural loads will be light, and that grading will be minimal, with construction generally occurring at or near the existing grades. If the proposed construction is significantly different from that described above or depicted in this report, we should be notified to reevaluate the recommendations contained in this report.

SITE CONDITIONS

The project site is located at the Del Norte Senior High School in Del Norte, Colorado. The existing school includes a main school building with a rough footprint area of about 35,000 SF, and a detached gym with an area of about 25,000 SF. The school building is a single story brick structure, and the gym is a concrete and steel structure that stands about 1½ to 2 stories tall. Both buildings appeared to be in good condition at the time of our visit. Parking Lots are located in the front of each building, with a larger parking lot located at the gym building, and a drive area that separates the two buildings. In general, the pavement was in poor condition,

- 3 -with substantial lateral, longitudinal, and fatigue cracking noted. Vegetation at the site was relatively sparse, with some small trees bordering the buildings, and grasses and weeds throughout the site. Bedrock outcrops were observed behind the school along the west end of the site. No surface water features were observed, but a small drainage swale was observed along the north side of the site.

SUBSURFACE CONDITIONS

Information on subsurface conditions was obtained by conducting a site reconnaissance, drilling four exploratory borings, three percolation test holes, and hand excavating two exploratory pits at the approximate locations shown on Fig. 1. The boring logs and corresponding legend and notes are shown on Figs. 2 and 3. The results of laboratory testing performed on selected representative samples from the borings are presented on Figs. 4 and 5, and are summarized on Table I. The laboratory testing was conducted in general accordance with applicable ASTM standards.

Below asphalt, concrete, or topsoil, the subsurface profile generally consisted of poorly graded alluvial gravel with silt and sand overlying very hard ash-flow tuff bedrock extending to the maximum explored depths of 5 to 20 feet. The native gravel was poorly graded, with silt and sand, and included cobbles. It was very dense, slightly moist to moist, and brown to light brown in color. Fill was found extending to a depth of 3 feet in Boring 2 and appeared to consist of reworked onsite gravels. The fill was similar to the native soils, but was looser, contained slightly more clays, and had a mottled appearance. The ash-flow tuff bedrock was very hard, and buff to orange brown in color. Although drilling progress was somewhat slower in the bedrock, no auger refusal was encountered.

Two hand excavations were dug at the rear of the building at the areas shown on the attached

Fig. 1. to attempt to determine the existing foundation type. A footing was exposed at an approximate depth of 3 feet at the north excavation, but no footing was exposed on the south excavation. Based on the subsurface conditions encountered, we expect that the existing foundations are shallow.

Groundwater was not encountered in the borings when measured the day of drilling.

Fluctuations in the water level will likely occur with time due in particular to seasonal and climatic changes. Because of the presence of shallow, relatively impervious bedrock, it is likely that groundwater will be shallow after significant precipitation or other wetting events.

- 4 -

ENGINEERING CONSIDERATIONS

Based on the data obtained during the field and laboratory studies, very hard bedrock is expected to be encountered near the elevation of a shallow footing. The bedrock is non-expansive, and will be suitable for the support of a shallow foundation. Alternatively, foundations can be placed on well compacted structural fill. We recommend that the entire foundation system bear on either bedrock or structural fill to reduce the potential for differential settlement. A detailed discussion is presented in the “Subgrade Preparation” subsection of the “Site Grading” section herein. The existing site soils will be suitable for use as structural fill if processed to remove oversized materials. If it is encountered below the footing elevation in the area of the proposed addition, man-placed fill should be removed, processed, and replaced in well compacted lifts in accordance to the specifications provided herein.

SHALLOW FOUNDATIONS

The design and construction criteria presented below should be observed for a shallow footing system. The construction details should be considered when preparing project documents.

1. We recommend foundations be constructed directly on bedrock or well compacted structural fill. Footings constructed on bedrock can designed for a maximum allowable bearing pressure of 5,000 psf. Footings constructed on well compacted structural fill can be designed for a maximum allowable bearing capacity of 3,500 psf. These bearing pressures may be increased by a factor of 1/3 for transient loadings. Compaction specifications, and a discussion regarding the suitability for reuse of the on-site soils is presented under the “Site Grading” section.

2. We estimate total settlement for shallow foundations designed and constructed as discussed in this section will not exceed approximately 1 inch. Settlement of the addition will be differential to the existing structure, and should be considered in the plan details.

3. Continuous footings should have a minimum width of 16 inches, and isolated pads should have a minimum width of 24 inches.

4. Exterior footings and footings beneath unheated areas should be provided with adequate soil cover above their bearing elevation for frost protection. Based on our

- 5 -experience with similar projects, we recommend the foundations be placed at least 36 inches below the existing grade.

5. The lateral resistance of a foundation placed on properly compacted fill material or bedrock will be a combination of the sliding resistance of the footing on the foundation materials and passive earth pressure against the side of the footing. Resistance to sliding at the bottoms of the footings may be calculated based on an allowable coefficient of friction of 0.35. Passive pressure against the sides of the footings may be calculated using an allowable equivalent fluid unit weight of 190 pcf. These values are working values. The specifications for compaction of fill against the sides of foundations to resist lateral loads are presented under the “Site Grading” section of this report.

6. Earthwork recommendations for shallow foundations are presented in the “Site Grading” section of this report.

7. Existing fill, or areas of loose material encountered within the foundation excavation should be removed and the footings extended to adequate natural bearing material.

8. Granular foundation soils should be densified with a smooth vibratory compactor prior to placement of concrete.

9. A representative of the geotechnical engineer should observe all footing excavations prior to fill and concrete placement.

FLOOR SLABS

The natural on-site soils, exclusive of topsoil, are suitable to support lightly to moderately loaded slab-on-grade construction. To reduce the effects of some differential movement, floor slabs should be separated from all bearing walls and columns with expansion joints which allow unrestrained vertical movement. Floor slab control joints should be used to reduce damage due to shrinkage cracking. Joint spacing is dependent on slab thickness, concrete aggregate size, and slump, and should be consistent with recognized guidelines such as those of the

Portland Cement Association (PCA) and American Concrete Institute (ACI). The joint spacing and slab reinforcement should be established by the designer based on experience and the intended slab use.

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If moisture-sensitive floor coverings will be used, mitigation of moisture penetration into the slabs such as by use of a vapor barrier, may be required. If an impervious vapor barrier membrane is used, special precautions will be required to reduce differential curing problems which could cause the slabs to warp. Section 302.1R of the ACI Manual of Concrete Practice addresses this topic.

WATER SOLUBLE SULFATES

The concentrations of water soluble sulfates measured in samples of the native gravel and fill obtained from the exploratory borings ranged from 0.01 to 0.02 percent. These concentrations of water soluble sulfates represent a Class 0 severity of exposure to sulfate attack on concrete exposed to these materials. The degree of attack is based on a range of Class 0 to Class 3 severity of exposure as presented in ACI 201. Based on the laboratory data and our experience, special sulfate resistant cement will not be required for concrete exposed to the on-site soils.

SEISMIC DESIGN CRITERIA

Using estimated shear wave velocities for the subgrade materials encountered based on standard penetration testing, calculations indicate a design Site Class C per the International

Building Code (IBC). Based on the subsurface profile and the anticipated ground conditions, liquefaction is not a design consideration.

SURFACE DRAINAGE

Providing proper surface drainage, both during construction and after the construction has been completed, is very important for acceptable performance of the development. The following recommendations should be used as guidelines and changes should be made only after consultation with the geotechnical engineer.

1. Excessive wetting or drying of the foundation and slab subgrades should be avoided during construction.

2. Care should be taken when compacting around the foundation walls to avoid damage to the structure.

3. The ground surface surrounding the exterior of the building should be sloped to drain away from the foundation in all directions. We recommend a minimum slope of 6 inches in the first 10 feet in unpaved areas. Site drainage beyond the 10-foot zone should be

- 7 -designed to promote runoff and reduce water infiltration. A minimum slope of 3 inches in the first 10 feet is recommended in the paved areas. These slopes may be changed as required for handicap access points in accordance with the Americans with

Disabilities Act.

4. Ponding of water should not be allowed on backfill material or within 10 feet of the foundation walls, whichever is greater.

5. Roof downspouts and drains should discharge well beyond the limits of all backfill.

SITE GRADING

We recommend the following criteria be used when preparing the site grading plans.

Fill Material Specifications: The following material specifications are presented for fills on the project site.

1. Fill Beneath and Beside Foundations: The on-site soils with the exception of any deleterious materials and rock larger than 4 inches in diameter will be suitable for reuse as structural fill. The bedrock can also be used for structural fill if it is processed into a soil like material, with a maximum particle size of about 4 inches. Import fill, if required, should consist of a minus 2-inch nonexpansive soil having a maximum 30% passing the

No. 200 sieve and a maximum plasticity index of 15. New fill should extend down from the edges of the foundations at a minimum 1:1 horizontal to vertical projection.

2. Pavement subgrade areas: Same as #1 above.

3. Pipe Bedding Material: Pipe bedding material should be a free draining, coarse-grained sand and/or fine gravel having a maximum size of 1 inch. We do not anticipate that the near surface on-site natural soils will be suitable for bedding due to the presence of larger particles.

4. Utility Trench Backfill: Materials excavated from the utility trenches may be used for trench backfill above the pipe zone fill provided they do not contain unsuitable material or particles larger than 4 inches.

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5. Material Suitability: All fill material should be free of vegetation, brush, sod and other deleterious substances. Fill should not contain concentrations of organic matter or other deleterious substances. The geotechnical engineer should evaluate the suitability of all proposed fill materials prior to placement.

Subgrade Preparation: The ground surface shall be stripped of vegetation/organics prior to foundation or fill placement. Loose, unstable or otherwise unsuitable soils shall be removed, where present, in order to provide a stable platform prior to placement of fill. If bedrock is only encountered in portions of the foundation excavation, we recommend that the footings either be extended to bedrock throughout, or that the areas where bedrock is encountered are over-excavated to a depth of 12 inches below the bearing elevation in order to provide a consistent bearing surface.

Compaction Requirements: A representative of the geotechnical engineer should observe fill placement operations on a full-time basis. We recommend the following minimum compaction criteria be used on the project.

Area Percentage of Modified Proctor

Maximum Dry Density (ASTM D1557) Fill beneath foundations 95% Foundation wall backfill 90% Slab Subgrade 90% Beneath pavement Areas/ Flatwork/Utility Trenches

90%

Landscape and Other Misc. Overlot Fill Areas 90%

For compaction of suitable granular soils, a moisture content near optimum should be maintained.

PAVEMENT DESIGN

A pavement section is a layered system designed to distribute concentrated traffic loads to the subgrade. Performance of the pavement structure is directly related to the physical properties of the subgrade soils, pavement section, and traffic loadings. The number and magnitude of wheel loads are major factors for pavement design.

Subgrade Materials: Based on the American Association of State Highway Transportation

Officials (AASHTO) classification system the soils tested near the proposed subgrade elevation

- 9 -mostly consisted of A-1-a A-1-b soils with some A-2-4 soils also found. A maximum group index of 0 was determined. Based on the subsurface conditions encountered, a design R-value of 20 was used for design purposes, resulting in a resilient modulus of 4,940 psi. A subgrade modulus of 150 pci was used for rigid pavement sections.

Design Traffic: We have assumed traffic will primarily consist of automobile (and light passenger vehicles), with occasional truck traffic, to consist of trash trucks, and single unit delivery trucks. Based on our experience with similar-facilities, for our pavement thickness design calculations, we assumed an equivalent 18-kip daily load application (EDLA) of 5 for areas restricted to automobile traffic (such as parking stalls), and 10 for areas of combined auto and truck traffic (such as drive lanes). If it is determined that actual traffic is significantly different from that estimated, we should be contacted to reevaluate the pavement thickness design.

Pavement Sections: The recommended sections were determined using the 1993 AASHTO pavement design procedures. Based on the subgrade conditions encountered and the estimated traffic information, we recommend the following pavement sections:

Pavement Section Thickness (in.)

Full Depth

Asphalt Composite Asphalt over Base Course

Portland Cement Concrete over Base

Course Areas Restricted to Automobiles

(i.e. parking stalls) 5 4 over 6 6 over 4

Areas with Automobiles, Buses, and Occasional Trucks

(i.e. drive lanes)

5.5 4.5 over 6 6 over 4

We recommend drive through lanes, trash pickup areas, and any areas where truck turning movements are concentrated be paved with 6 inches of Portland cement concrete (PCC). The use of a flexible pavement in these areas could result in rutting/shoving of the pavement due to the concentrated wheel loads. To develop a stable subgrade, a minimum section of 4 inches of aggregate base course material should be placed below PCC pavement sections.

Subgrade Preparation: Some unstable subgrade areas may be present at this site. Detailed recommendations regarding stabilization can be found in the “Subgrade Stabilization” subsection below. For general subgrade preparation, we recommend the pavement subgrade

- 10 -be thoroughly scarified and well-mixed to a minimum depth of 12 inches and adjusted to a minimum of 90 percent of the maximum dry density at a moisture content within 2 percent of optimum as determined by the modified proctor (ASTM D1557).

Proof Roll: Before paving, the subgrade should be proof rolled with a heavily loaded, pneumatic-tired vehicle. The vehicle should have a gross weight of at least 50,000 pounds, with a single loaded axle weight of 18,000 pounds, and a tire pressure of 100 psi. Areas that deform excessively under heavy wheel loads are not stable and should be removed and replaced with suitable material to achieve a stable subgrade prior to paving.

Subgrade Stabilization: Areas of unstable subgrade soils may be encountered during subgrade preparation for construction of the new pavement. Unstable foundation soils may be stabilized by overexcavation and replacement of the subgrade with suitable, imported, angular, well-graded materials. Other alternatives include the use of Type 2 biaxial geogrid reinforcement in combination with a layer of Class 6 aggregate base course. It has been our experience that the use of a crushed concrete product meeting a Class 6 gradation can perform well when trying to achieve stabilization. Specific stabilization requirements should be evaluated at the time of construction.

Drainage: The collection and diversion of surface drainage away from paved areas is extremely important to the satisfactory performance of the pavement. Drainage design should provide for the removal of water from paved areas and prevent wetting of the subgrade soils. Water entering through cracks and joints and in poorly drained areas adjacent to the pavement can allow water to saturate the pavement subgrade soils causing them to lose strength and result in pavement failure. A means of preventing water from entering and migrating below the pavement should be included in the design considerations of the paved areas.

Maintenance: Periodic maintenance of paved areas is critical to achieve the design life of the pavement. Crack sealing should be performed annually as new cracks appear. Chip seals, fog seals, or slurry seals applied at approximate intervals of 3 to 5 years are usually necessary for asphalt. As conditions warrant, it may be necessary to perform patching and structural overlays at approximate 10-year intervals.

Pavement Materials: The asphalt should consist of a mixture of aggregate, filler and asphalt cement established by a qualified engineer. Asphalt cement with a performance grade of 58-28

- 11 -is commonly used in this area and will likely be acceptable for this project. Asphalt cement with a performance grade of 64-22 will also be acceptable but may be more prone to thermal cracking. The appropriate asphalt cement content should be determined by the mix design.

Aggregate Base Course should conform to the requirements of AASHTO M147 and to Section

703.03 of the Colorado Department of Transportation (CDOT) Standard Specifications for Road and Bridge Construction and should meet Class 6 grading and quality as defined by the CDOT specifications. The aggregate should have a minimum R-value of 78. The asphalt and aggregate base course also should meet any other applicable Town or County standards.

Concrete pavement should meet the requirements of a Class P Mix, per Section 601 of the CDOT

Standard Specifications, and should be based on a mix design established by a qualified engineer. The concrete should contain joints not greater than 12 to 15 feet on centers. The joints should be hand formed, sawed or formed by premolded filler. The joints should be at least 1/4 of the slab thickness. Expansion joints should be provided at the end of each construction sequence and between the concrete slab and adjacent structures. Expansion joints where required, should be filled with a ½ inch-thick asphalt impregnated fiber. Concrete should be cured by protecting against loss of moisture, rapid temperature changes and mechanical injury for at least three days after placement. The concrete sections presented above are assumed to be unreinforced.

Providing dowels at construction joints would help reduce the risk of differential movements between panel sections. Providing a grid mat of deformed rebar or welded wire mesh within the concrete pavement section would assist in mitigating corner breaks and differential panel movements. If a rebar mat is installed, we recommend that the bars be placed in the lower half of the pavement section. A structural engineer should evaluate the placement and spacing of rebar if needed.

WATER QUALITY POND

One exploratory boring and 3 percolation test holes were drilled at the locations shown on the

Attached Fig. 1. A layer of alluvial gravel overlying relatively shallow bedrock was encountered.

Although the overlying gravel showed a high infiltration rate, a discounted infiltration rate should be used if the proposed pond will be near the relatively impervious bedrock interface.

Infiltration Rates: Percolation tests were performed in Percolation Test Holes 1, 2, and 3 in accordance with a modified percolation test procedure whereby the infiltration rate is determined by applying a reduction factor to the measured percolation rate to account for the

- 12 -exfiltration occurring through the sides of the percolation hole. The measured percolation rates and associated infiltration rates of the soils tested are presented below. The measurements were made at 15-minute intervals. The values presented reflect the average of the last three readings made at each test hole.

Boring Average Percolation Rate (inches per hour)

Correction Factor Infiltration Rate (inches per hour)

1 127 21 6.0

2 138 21 6.6

3 110 20 5.5

Average Infiltration Rate 6

Based on the measured infiltration rates and the subsurface conditions encountered, a

Hydrologic Soil Group (HSG) of “A” was determined for the soils within the proposed detention pond in accordance with the criteria listed in the United States Department of Agriculture’s

National Engineering Handbook, Part 630: Hydrology. Group A soils generally have low runoff potential when thoroughly wet. This classification should be lowered to an HSG of “D” if the base of the pond will be constructed within an elevation of 2 feet from the high-water table as measured during any month of the year. A long-term water level study would be required to determine the high-water table, and was not part of the scope of this project.

EXCAVATION CONSIDERATIONS

In our opinion, the overburden soils and near surface bedrock encountered in the exploratory borings drilled for this study can be excavated to the anticipated depths of about 5 feet or less with hydraulic chisels, and heavy-duty construction equipment equipped with rippers. Harder zones of bedrock may be encountered within the excavation in portions of the site, and in particular confined excavations such as trench cuts. If harder rock is encountered, some blasting may be required.

All excavations should be in accordance with OSHA, state and local requirements. The contractor should follow appropriate safety precautions. In accordance with OSHA guidelines, the native overburden soils will classify as a Type C material. If materials different from those indicated in this report are encountered, the OSHA soil type may vary and need to be adjusted.

Per OSHA criteria, unless excavations are shored, temporary excavations in Type C materials should have slopes no steeper than 1½:1 (H:V). The bedrock will likely classify as a Type B soil requiring temporary slopes no steeper than 1:1. Shoring will be required where excavated

- 13 -slopes cannot be accommodated. The contractor’s competent person should make decisions regarding cut slopes.

Groundwater was not encountered during the subsurface investigation and is not anticipated during construction. Where groundwater is encountered, flatter slopes will be required. It is assumed site dewatering would occur in advance of the excavation, and be maintained the entire duration that the excavation is open. Surface drainage should be diverted away from all temporary cut slopes in order to reduce the potential for slope erosion and instability. OSHA regulations require that excavations greater than 20 feet in depth and excavations that extend below the ground water level be designed by a professional engineer.

DESIGN AND SUPPORT SERVICES

Kumar & Associates, Inc. should be retained to review the project plans and specifications for conformance with the recommendations provided in this report. We are also available to assist the design team in preparing specifications for geotechnical aspects of the project and, if necessary, perform additional studies to accommodate any changes in the proposed construction.

We recommend that Kumar & Associates, Inc. be retained to provide construction observation and testing services to document that the intent of this report and the requirements of the plans and specifications are being followed during construction. This will allow us to identify possible variations in subsurface conditions from those encountered during this study and to allow us to re-evaluate our recommendations, if needed. We will not be responsible for implementation of the recommendations presented in this report by others, if we are not retained to provide construction observation and testing services.

LIMITATIONS

This study has been conducted for exclusive use by the client for geotechnical related design and construction criteria for the project. The conclusions and recommendations submitted in this report are based upon the data obtained from the exploratory borings/pits at the locations indicated on Fig. 1 or as described in the report, and the proposed type of construction. This report may not reflect subsurface variations that occur between the exploratory borings/pits, and the nature and extent of variations across the site may not become evident until site grading and excavations are performed. If during construction, fill, soil, rock or water conditions appear to be different from those described herein, Kumar & Associates, Inc. should be advised

- 14 -at once so that a re-evaluation of the recommendations presented in this report can be made.

Kumar & Associates, Inc. is not responsible for liability associated with interpretation of subsurface data by others.

The scope of services for this project does not include any environmental assessment of the site or identification of contaminated or hazardous materials or conditions. If the owner is concerned about the potential for such contamination, other studies should be undertaken.

AFK:bj

BORING

DEPTH

(ft)

GRAVEL

SAND

LIQUID

LIMIT

PLASTICITY

INDEX

1 2 7/18/19 7.7 86.2 0.01 Poorly Graded Gravel with Silt and Sand (GP-GM)

2 1 7/18/19 4.2 115.9 64 27 9 23 7 0.02 A-2-4 (0) Fill: Poorly Graded Gravel with Silty Clay and Sand (GP-GC)

3 1 7/18/19 8.5 95.2 52 37 11 NP A-1-a (0) Well Graded Gravel with Silt and Sand (GW-GM)

4 1 7/18/19 3.5 115.1 41 52 7 NP A-1-a (0) Poorly Graded Sand with Silt and Gravel (SP-SM)

SUMMARY OF LABORATORY TEST RESULTS

SAMPLE LOCATION

NATURAL

MOISTURE

CONTENT

Project Name : Rio Grande NFSO

DATE

TESTED

WATER

SOLUBLE

SULFATES

GRADATION

SOIL OR BEDROCK TYPE

(Unified Soil Classification)

Kumar and Associates, Inc.

Project No.: 19-2-178

Date Sampled: 7/11/2019 Date Received: 7/15/2019

AASHTO

CLASSIFICATION

(Group Index)

PERCENT

PASSING NO.

200 SIEVE

ATTERBERG LIMITS

NATURAL

DRY

DENSITY

(pcf)

TABLE I