Geotech survey 2015.pdf

You Just Can’t Turn It Off

REVISED GEOTECHNICAL STUDY

USDA Moore Air Base (MAB) Mexican Fruit Fly Rearing Facility

22675 N. Moorefield Road Edinburg, Texas 78541

PREPARED FOR:

International Consulting Engineers 1722 N. Closner Blvd. Suite B Edinburg, Texas 78541

PREPARED BY:

RGV Strata 717 West 2nd Street Mercedes, Texas 78570

June 6, 2016 RGV Strata Project No. 161021

Geotechnical Construction QA/QC

RGV Strata 717 West 2nd Street

Mercedes, Texas 78570

June 6, 2016

Attention: Mr. Hugo P. Gonzalez, Jr., PE, PMP, CFM

International Consulting Engineers

1722 N. Closner Blvd. Suite B

Subject: Geotechnical Engineering Study USDA MAB Mexican Fruit Fly Rearing Facility 22675 N. Moorefield Road

We are pleased to submit this report of our geotechnical study for the project. This study was performed in general accordance with our Proposal No. R-16006, dated February 2, 2016, and your authorization.

The purpose of our study was to examine the geotechnical profile at the site in order to evaluate the subsurface soils and their engineering properties. This information was used to develop geotechnical engineering recommendations for project design and construction.

A brief summary of finding and recommendations provided in the full report are outlined below.

The explorations and laboratory testing performed as part of the investigation generally encountered:

Near surface materials generally consist of clayey sand and/or sandy lean clay

Existing elevation is approximately at 216-feet

Deeper soils general consist of similar soils as the near surface material

We encountered subsurface water approximately 27 to 28-feet below existing elevations during drilling operations

Subsurface water was observed at approximately 17-feet and cave-in was observed at approximately 18 to 19-feet

Standard Penetration Testing (SPT) indicate the near surface sandy soils are generally medium dense

SPT indicate the near surface clayey soils are generally stiff

Laboratory testing indicates the near surface soils have low shrink-swell potential

Laboratory testing indicate the soils appear to have low to moderate contents of soluble sulfate.

Table of Contents Page i of i April 10, 2016

1.0 PROJEC UNDERSTANDING

2.0 SCOPE OF WORK

3.0 FINDINGS

3.1 Current Site Conditions

3.2 Subsurface Conditions

3.3 Groundwater

3.4 Expansive Soils

4.0 RECOMMENDATIONS

4.1 Earthwork

4.1.1 Site Preparation

4.1.2 Fill Materials

4.1.3 Compaction

4.1.4 Workability

4.1.5 Excavation Conditions

4.1.6 Temporary Excavations

4.2 Foundation Design Recommendations

4.2.1 Slab on Grade with Grade Beams

4.2.2 Spread Footings

4.2.3 Drilled-Shaft Foundations

4.2.4 Foundations Subject to Uplift

4.3 Seismic Design Considerations

4.4 Concrete Slabs on Grade

4.5 Pavement Structures

4.6 Sulfate Concentration & Concrete

4.7 Site Drainage

4.8 Pre-Construction Conference

4.9 Construction Observation and Testing

5.0 LIMITATIONS

Appendices

Appendix A Figures Appendix B Explorations Appendix C Laboratory Testing

Page 1 of 15 June 6, 2016

Geotechnical Study

In accordance with our proposal dated February 2, 2016, and your authorization, we have performed a geotechnical evaluation for the USDA MAB Mexican Fruit Fly Rearing Facility located at 22675 N.

Moorefield Road in Edinburg, Texas. The purpose of this study was to examine the geotechnical profile at the site in order to evaluate the subsurface soils and their engineering properties. This information was used to develop geotechnical engineering recommendations for project design and construction. A description of the project, the scope of our geotechnical services, a description of our findings and our recommendations are presented in the following sections.

1.0 PROJECT UNDERSTANDING

This project consists of the design and construction of a new Mexican Fruit Fly Rearing Facility with several amenity structures. The main rearing facility will a have a 115,000 square foot plan area and the amenity structures will be approximately 2,500 square feet in plan area. The structures may be supported on shallow or deep foundations. Steel framing or CMU block are anticipated to support the roof system.

Miscellaneous mechanical and/or electrical equipment should be supported on shallow equipment pads.

We understand that existing elevation is approximately 216-feet and the finished floor elevation is between 217.5 to 218-feet. Associated paving and utilities are also included for this project.

2.0 SCOPE OF WORK

The scope of our services for this study included:

Aerial Photo Review with Boring Locations

Soil Reviews

Borings Engineering Analysis

Construction and Design Recommendations

Laboratory Testing

Our scope of services for this study did not include environmental consulting services with respect to the identification or assessment of any hazardous environmental or biological materials that may be, or may not be, present at the site.

3.0 FINDINGS

This section contains the results of our evaluation of the site as determined by the scope described in

Section 2.0.

3.1 Current Site Conditions

The project site is located Moore Air Base on the west side of the facility. The plan structure will be placed on an open grass area and an existing citrus orchard north of the runways. There are currently multiple existing structures within the facility including runways, a water tower, water treatment facility, and multiple warehouses. Based on the elevations provided by I.C.E. the project site is on the order of 216 feet relative to mean sea level.

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3.2 Subsurface Conditions

The soils encountered from the surface to the boring termination depth were generally a sandy lean clay or a clayey sand. Moisture contents of the material ranged between 4 and 35 percent. Near surface material was generally medium stiff or medium dense. Boring terminating at 20 feet or more were generally hard or very dense.

3.3 Groundwater

Subsurface water was encountered in five of our test borings during the field exploration. Subsurface water was encountered in the boring terminating at depth of 30 feet. Subsurface water was observed at approximately 28-feet during drilling operations and observed at approximately 17.5-feet, 24-hours after the completion of drilling operations. Cave-in was observed at about 18-fet. We did not perform long term monitoring of groundwater levels at the site.

3.4 Expansive Soils

The soils encountered in our explorations consist of clayey sands and sandy lean clays with low plasticity that exhibits low swell potential when compacted and inundated with water while subject to light loading similar to a floor-slab. On-site soil materials as engineered fill beneath structures may be utilized.

Potential vertical soil movements were estimated using the Texas Department of Transportation method

TEX-124-E, Potential Vertical Rise. This method utilizes the soils in-situ moisture conditions and plasticity characteristics within the active zone. It is estimated that the depth of the active zone at this site is approximately 15 feet. The estimated Potential Vertical Rise (PVR) values for the dry and average moisture conditions of subgrade soils are less than 1-inch. A sustained surcharge load of 1.0 pound per square inch was used to calculate the existing PVR. It is noted that the PVR estimates are provided as an indicator of the severity of potential soil movements at this site and are not intended as a prediction of actual foundation movements. Additional details concerning the use of on-site soils as fill material are provided in Section 4.1.2.

4.0 RECOMMENDATIONS

The following sections provide our recommendations for the design and construction of the project. We should be contacted for additional recommendations if the proposed construction or anticipated foundation loads are changed from the project description in Section 1.0 of this report, or if significant changes occur at the site with respect to the site conditions described in Section 3.1 of this report.

4.1 Earthwork

Recommended site grading for roadways and structures are presented below.

4.1.1 Site Preparation

The area covered by these recommendations should cover a construction envelope that extends at least

5 feet beyond the actual limits of the structures’ footprint (buildings or pavements). Finished grade is defined as the lowest point within any structure’s building envelope.

1. Prior to general site grading the site should be stripped of any existing debris, and vegetation. All debris or other deleterious materials should be excavated and disposed of off-site at a legal dumpsite.

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Prior to placing new fills, all areas should be observed by a representative of the geotechnical engineer for evidence of any remaining undesirable materials.

2. Undisturbed native soils are generally suitable for support of planned footings or engineered fill if required for site grading.

3. Prepare the ground surface in fill areas and in areas cut to grade by scarifying the soils to a depth of

10 inches, moisture-conditioning, and compacting.

4. The possible re-use of on-site soil in newly compacted fill and the requirements for imported fill soil is discussed in Section 4.1.2.

5. Compact subgrade, fill, backfill, subbase fill, or base material to the relative compaction and moisture content noted in the Section 4.1.3. Lift thickness for engineering fill will be dependent upon the type of compaction equipment utilized, but should generally be placed in lifts not exceeding 8 inches in loose thickness and 6 inches compacted thickness. Fills should be moisture conditioned and compacted by appropriate mechanical methods.

6. The PVR at the site is less than 1-inch and for drainage purposes the building pads should be at least one (1) foot above the approximate existing elevation of 216-feet. The anticipated amount of compacted engineering fill is 18-inches after the removal of organic debris. The finished pad elevation should be about 217-feet above the average mean sea level and compacted as per the recommendations presented in Section 4.1.3.

4.1.2 Fill Materials

On-site and imported soils that exhibit low expansive potential when compacted are generally suitable for re-use as fill in all areas provided they are free of debris and organic material, and all particles are less than 3 inches in size.

On-Site Soils

The on-site soils tested in the laboratory exhibit low swell potential and appear suitable for use as engineered fill material below structures and slabs.

Imported Soils

Soils imported from off-site sources for use in new fills below structures or rigid concrete pavements should meet the requirements listed in the following table:

Property Specification Remarks

Maximum Particle Size 3 inches None

Percent Passing No. 200 Sieve 20 to 70 None

Plasticity Index 7 to20 None

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The geotechnical consultant should evaluate any imported materials and details of their placement prior to importation.

4.1.3 Compaction

We recommendation subgrade, fill, backfill, subbase fill, or base material be prepared and placed to the relative compaction and moisture content are provided below. Lift thickness for backfill will be dependent upon the type of compaction equipment utilized, but should generally be placed in lifts not exceeding 8 inches in loose thickness and compacted to a maximum of 6-inch thickness. Fills should be moisture conditioned and compacted by appropriate mechanical methods.

Recommendations for Compaction of On-Site Soils

Material / Location

Percent Compaction

(ASTM D 698)

Moisture Content Range

(ASTM D 698)

Building Pad Subgrade 95 min. Opt. to Opt +3 percent

Below Foundations 95 min Opt. -2 to Opt. +2 percent

Above Foundation Level and Below Concrete Slabs or Flatwork

95 min. Opt. -2 to Opt. +2 percent1

Trench backfill, upper 2 ft.– granular fill 95 min. Opt. -2 to Opt. +2 percent

Trench backfill, upper 2 ft.– clayey fill 95 min. Opt. -2 to Opt. +2 percent

Notes:

1. Maintain in a moist condition until overlying structures, slabs, or pavements are constructed

Recommendations for Compaction of Imported Soils

Material / Location

Percent Compaction

(ASTM D 698)

Moisture Content Range

(ASTM D 698)

Below Foundations 95 min. Opt. -2 to Opt. +2 percent

Above Foundation Level and Below Concrete Slabs or Flatwork

95 min. Opt. -2 to Opt. +2 percent1

Trench backfill, upper 2 ft.– granular fill 95 min. Opt. -2 to Opt. +2 percent

Trench backfill, upper 2 ft.– clayey fill 95 min. Opt. -2 to Opt. +2 percent

1. Maintain in a moist condition until overlying structures, slabs, or pavements are constructed

4.1.4 Workability

If site grading is performed during or subsequent to wet weather, or if ponding is present, then near-surface site soils may be above optimum moisture content. This could make it difficult to achieve specified compaction, material pumping, and equipment maneuverability problems. If this occurs, disking for aeration followed by sufficient drying time (possibly several days depending upon the weather), chemical

Page 5 of 15 June 6, 2016 treatment, replacement with drier material, stabilization with a geotextile fabric or grid, or other methods may be implemented to reduce excessive soil moisture or otherwise facilitate earthwork operations.

Wet to saturated sandy lean clay soils could be encountered to significant depths below the existing ground. This is most likely to occur if site grading is performed during or subsequent to wet weather, or if ponding is present. These soils will be difficult to process and will not be a suitable surface to place engineered fill. If unsuitable soils are encountered at the site, the following options may be considered:

Disking for aeration followed by sufficient drying time (possibly several days depending upon the weather and degree of saturation)

Replacement with drier material

Although these first two options may be more cost effective than other methods they will likely require significant time and if the depth of the unsuitable material extends beyond more than a few feet the cost of these methods quickly escalates. As an alternative to these removal methods the following could be considered:

Stabilization with a geotextile fabric or grid - We recommend the use of 2 layers of geogrid to create a suitable base for structure foundations or embankment fills. Unsuitable subgrade soils within the footprint and extending 2 feet beyond the zone of unsuitable soils should be excavated

2 feet below the bottom of the proposed foundation elevation. A layer of Tensar BX1200 (or equivalent) geogrid should be placed at the base of the excavation and the excavation should be partially backfilled with engineered fill. After the placement of 1 foot (two lifts) of engineered fill a second layer of equivalent geogrid should be placed in the excavation and then the excavation can be backfilled with engineered fill to foundation bottom elevation or embankment fills can be placed.

Stabilization with lime or portland cement – The use of 6 to 12-inch-thick layer of lime or cement treated subgrade may also be considered for use as a “bridge” over unworkable subgrade soils.

The use of a test area with proof rolling is recommended to determine the optimum depth of treatment and percentage of admixture necessary given the range of adverse site conditions that could be encountered.

4.1.5 Excavation Conditions

Hollow-stem auger drilling methods were used to advance all of the borings to their planned termination depths. The drilling conditions encountered in our borings generally represent the conditions to be expected across the site; however, excavation conditions are dependent on many factors including:

variability of cementation, presence and size of cobbles and boulders, rock jointing, rock joint condition, degree of weathering, excavation size, excavation equipment, operator experience, and operator effort.

It may not be possible to correlate all of the potential variables with the results of what we experienced during our exploration advancement in terms of the actual excavation conditions that could be encountered. Those involved with the construction of this site should use the information provided in this report as a guideline for the conditions that generally exist only at each boring location. Those using this

Page 6 of 15 June 6, 2016 report should have an understanding of the limitations of the methods used to obtain the data and should use the information with caution and only as a guideline.

Those involved with the construction of this site should review this report along with appropriate performance charts prepared by the manufacturer of the planned excavation equipment. This information can be used to assist in the selection of appropriate equipment that will be required to excavate the material anticipated to be encountered at this site. However, those using the interpretation of the site conditions contained in this report for any reason do so at their own risk.

Prospective contractors should exercise caution and assume the associated risks if the information provided within this report is used to determine the suitability of any equipment used for construction of the proposed project.

4.1.6 Temporary Excavations

Those involved with the construction of this project should be aware that slope height, slope inclination, or excavation depths (including utility trench excavations) should in no case exceed those specified in local, state, and/or federal safety regulations (e.g., OSHA Health and Safety Standards for Excavations, 29

CFR Part 1926, or successor regulations). Such regulations are strictly enforced and, if they are not followed, the Owner, Contractor, and/or earthwork and utility subcontractors could be liable for substantial penalties.

Near-surface soils consist predominantly of clayey sand and sandy clay. These soils could be considered a Type B soil when applying the OSHA regulations. For this soil type OSHA recommends a maximum temporary slope inclination of 1:1 (H:V) or flatter for excavations 20 feet or less in depth. Steeper cut slopes may be utilized for excavations less than 5 feet deep depending on the strength, moisture content, and homogeneity of the soils as observed in the field. Flatter slopes and/or trench shields may also be required depending on conditions encountered along the slope face. Actual safe slope conditions should be determined and monitored in the field at the time of construction by an OSHA-qualified “competent person.”

Trenches over 20 feet deep (if needed) should be designed by the contractor’s engineer based on alignment-specific soil properties and settlement-sensitive features. Excavations encountering seepage, if any, should be evaluated on a case-by-case basis. Where the stability of structures is endangered by excavation operations, support systems such as shoring, bracing, or underpinning may be required to provide structural stability and to protect personnel working within the excavation. Shoring, bracing, or underpinning required for the project (if any) should be designed by a professional engineer registered in the State of Texas. In general, heavy construction equipment, building materials, excavated soil, and vehicular traffic should not be allowed within 1/3 the slope height from the top of any excavation, unless incorporated into the engineered design

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4.2 Foundation Design Recommendations

Recommendations for the design of foundations with respect to bearing capacity, estimated settlement, resistance to lateral loading, and other geotechnical considerations are provided in this section of the report. The parameters provided below are contingent on following the earthwork recommendations provided in the previous sections, maintaining and establishing adequate site drainage during construction and for the life of the structures. The following foundations systems may be considered to support the structures at the subject project site:

Slab on Grade with Grade Beams;

Spread Footing; and

Drilled Piers.

If conditions are encountered during construction that significantly differ from what is described in Section

3.0, RGV Strata should be notified to provide additional recommendations.

4.2.1 Slab on Grade with Grade Beams

Exterior (or turned down edges) and interior grade beams should be used to support concentrated loads and to stiffen the floor slab. The depth of exterior and interior grade beams can be varied according to the structural requirements of the floor slab. We recommend exterior grade beams extend at least 30-inches below the finished floor elevation. Interior grade beams should extend at least 24 inches below the finished floor elevation. Exterior and interior grade beams may be designed using an allowable net bearing pressure of 2,250 psf for sustained loading conditions, including dead and live loads.

The width of the grade beam should be designed such that the vertical pressure applied to the soil does not exceed the recommended bearing pressure. In any case, the width of the grade beam should be at least 12-inches to facilitate placement of the reinforcing steel. We do not recommend the use of void boxes below grade beams because of the potential to collect free water within the void space. Grade beams will also act as moisture barriers reducing moisture fluctuations beneath the slab. Deeper moisture barriers will provide better control of moisture fluctuations particularly during extended periods of dry or wet weather. The allowable soil bearing pressures may be increased by one-third when considering total loads including loads of short duration such as wind or seismic forces.

4.2.2 Spread Footings

Recommended bearing pressures for spread footings are presented in the table below. The average footing bearing pressure should not exceed the allowable equivalent uniform bearing pressure presented below. However, peak edge stresses may exceed this value as long as the resultant passes through the middle third of the footing base. Continuous footings should have a minimum width of 12 inches, and isolated column footings should have a minimum width of 24 inches. The allowable soil bearing pressures may be increased by one-third when considering total loads including loads of short duration such as wind or seismic forces.

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Footing Depth Below Finished Grade1

(ft) Bearing Material

Allowable Equivalent Uniform Bearing Pressure2

(psf)

3 to 4 Undisturbed Native Soil

2,500

Min 5.0 Undisturbed Native Soil

4,000

Notes:

1. Finished grade is defined as the lowest point within, and 5 feet beyond, the structure’s footprint.

2. The bearing pressures should be considered as gross pressures, which include the weight of any soil above footings.

An estimated unit weight of 120 pcf may be assumed for compacted soil above spread footings.

Total foundation settlements for the expected structural loading conditions are estimated to be less than about ¾-inch, provided foundation bearing soils remain at their present, natural moisture conditions.

Differential foundation settlements should be on the order of about ½- inch or less for these estimated total settlements. Additional post-construction settlements of roughly equal magnitude could be experienced following a significant moisture buildup in the bearing soils. Therefore, drainage should be addressed to prevent or minimize water from infiltrating into the soils beneath foundations.

4.2.3 Drilled-Shaft Foundations

Drilled shaft foundations may be considered for support of the structures at the site as an alternative to shallow foundations. The following table includes allowable axial capacities for design consideration as well as the parameters to assist the designer in considering reaction of piles subject to lateral loading. Pile reactions to lateral loading are typically analyzed using finite element computer methods such as L-Pile.

Depth Below

Existing Grade

(ft)

Effective In-Situ Density

(pcf)

Soil Friction Angle

(degrees)

Axial Capacity Lateral Resistance

Un-drained Cohesion

(psf)

Allowable End-

Bearing (psf)

Allowable Side

Friction1 (psf) p-y Modulus2

(pci) 50

5< -- -- -- -- -- -- --

5—10 105 -- 750 -- 600 -- 0.007

10—15 105 -- 1,000 12,000 1,000 -- 0.007

15—20 110 -- 1,500 15,000 1,000 -- 0.005

20—25 115 -- 1,750 18,000 1,200 -- 0.004

Notes:

1. Loading in compression or in up-lift

2. Stiffness modulus of cohesionless soils

3. Estimated strain corresponding to ½ the maximum principal stress difference

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Drilled shafts may be considered to act individually under lateral loading where the center-to-center shaft spacing is greater than 3 diameters in the direction normal to loading, and where the center-to-center shaft spacing is greater than 8 diameters in the direction parallel to loading. For shaft layouts not conforming to these criteria, the effect of shaft interaction should be considered in the design. The effect of group action for center-to-center spacing less than 8 diameters in the direction of loading may be considered using the following criteria:

Center to Center Shaft Spacing for In-Line Loading1

Ratio of Lateral Resistance of

Shaft in Group to Single Shaft

8D 1.00

6D 0.70

4D 0.40

3D 0.25

Note:

1. Where D is equal to the shaft diameter

The parameters for estimating the pile deflections under lateral loads are ultimate values and appropriate factors of safety should be applied. Drilled shaft deflections induced by lateral loading are affected through a coupled interaction of soil and shaft stiffness. The shaft’s diameter, length-to-diameter ratio, stiffness, and shaft-head degree-of-freedom, need to be accounted for in order to predict accurate displacement, bending moment stresses, and shear stresses. The load capacities provided only consider the stresses induced in the supporting soils; the structural capacity of drilled shafts should be checked to assure they can accommodate the stresses induced by axial and lateral forces.

Axial settlement of drilled shafts designed and constructed in accordance with the recommendations in this report should be less than 1-inch.

Excavating to proposed design depths should be possible with conventional drilled shaft equipment.

Oversize material and hard excavation conditions could be encountered below a depth of 10 feet. Caving soils could also be encountered and temporary casing or drilling slurry may be required. Temporary casing should also be considered at shaft locations adjacent to existing improvements, in order to reduce the potential for ground loss and movement. Any water that collects at the bottom of the shaft should be removed prior placement of reinforcing steel and concrete. Temporary casing or drilling slurry used for shaft construction should be withdrawn in a manner maintaining a sufficient head of drilling fluid or concrete to counteract earth and any hydrostatic pressures. Insufficient head could result in “necking” of the shaft and reduced capacity. Concrete placement through fee-fall methods may be possible in shafts less than 30-feet deep, as long as measures are provided to prevent concrete from striking steel reinforcement or the excavation sides during placement. Shaft concrete should have a relatively high fluidity when places in cased holes or through a tremie; a slump in the range of 6 to 8 inches is recommended.

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We recommend that all drilled shaft installations be observed on a full-time basis by an experienced geotechnical engineer in order to evaluate that the soils encountered are consistent with the recommended design parameters.

4.2.4 Foundations Subject to Uplift

Concrete foundations subject to uplift may be designed using the “cone method”. The resistance for foundation cast against undisturbed native soils, or properly compacted engineered fill may be determined as follows:

𝑇𝑢 = 0.8 × 𝛾𝑚 × 𝐷2 × (𝐵 + 𝐿) +𝑊

Where:

𝑇𝑢 Ultimate uplift capacity (lbs) 𝛾𝑚 In-situ unit weight of the native soil or compacted fill (pcf)

D Depth to base of foundation below finish grade (ft)

B Width of foundation (ft)

L Length of foundation (ft)

W Weight of foundation including soil above the footing block (lbs)

We recommend an in-situ unit weight of 120 pcf for undisturbed native soil (m), and a unit weight of

115 pcf be used for engineered fill composed of on-site materials.

4.3 Seismic Design Considerations

Based upon a review of Section 11.4.1 Earthquake Loads – Site Ground Motion of the 2010 Edition of ASCE

7, the site is located in a zone where the peak ground accelerations having 2 percent probability of being exceeded in 50 years is 0.04. This ground motion value was calculated for "very dense soil" sites, which correspond to a shear-wave velocity of approximately 2,500 feet per second in approximately the top 100 feet bgs. Different soil or rock types may amplify or de-amplify these values.

The proposed improvements should be designed in accordance with the requirements of governing jurisdictions and applicable building codes. The following table presents the seismic design parameters for the site in accordance with ASCE 7-10 guidelines and mapped spectral acceleration parameters (United

States Geological Survey [USGS], 2011):

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Seismic Design Factors Value

Site Class C

Fa, Site Coefficient 1.2

Fv, Site Coefficient 1.7

Ss, Mapped Spectral Acceleration at 0.2-second Period 0.080 g

S1, Mapped Spectral Acceleration at 1.0-second Period 0.025 g

SMS, Spectral Acceleration at 0.2-second Period Adjusted for Site Class 0.096

SM1, Spectral Acceleration at 1.0-second Period Adjusted for Site Class 0.043

SDS, Design Spectral Response Acceleration at 0.2-second Period 0.064

SD1, Design Spectral Response Acceleration at 1.0-second Period 0.029

The proposed improvements should be designed in accordance with the requirements of governing jurisdictions and applicable building codes. The following table presents the seismic design parameters for the site in accordance with Minimum Design Loads for Buildings and Other Structures (American

Society of Civil Engineers ASCE/SEI 7-10) guidelines and mapped spectral acceleration parameters (United

States Geological Survey [USGS], 2011):

The previous table does not consider conditions where embankments may impound water. Site grading should be maintained and drainage of embankments should be provided so that water is not allowed to pond behind embankment slopes. RGV Strata should be consulted in order to provide additional analysis and recommendations for embankments that may retain water.

4.4 Concrete Slabs on Grade

All earthwork in slab support areas should be accomplished as recommended in Section 4.1 to provide subgrade support for slabs-on-grade. The design of the floor slabs is the responsibility of the structural engineer. However, from a geotechnical standpoint, we recommend the floor slab have a minimum thickness of 5 inches. Thicker slabs reinforced with steel as designed by a structural engineer will likely provide better performance and should be considered. Placement of the reinforcement in the slab is vital for satisfactory performance. Depending on reinforcement details, slabs-on-grade should be jointed in accordance with ACI (American Concrete Institute) or PCA (Portland Cement Association) guidelines, or as recommended by the structural engineer, to control shrinkage crack locations and/or provide load transfer where needed.

The need for a moisture-retarding system and/or vapor retarder should be considered by the structural engineer or architect, based on the moisture sensitivity of any anticipated flooring.

We recommend that slab concrete have a minimum compressive strength at 28 days of 3,000 psi. Upon delivery, concrete should be field-tested to identify the plastic properties of the fresh concrete and sampled for laboratory strength testing. Concrete placement and curing operations be performed in accordance with the ACI Manual. High water-cement ratio of the concrete and/or improper curing procedures used during either hot or cold weather conditions could lead to excessive shrinkage, cracking, Page 12 of 15 June 6, 2016 or curling in the slabs. High water-cement ratio and/or improper curing also greatly increase the water vapor permeability of concrete.

4.5 Pavement Structures

For the paved areas, we understand that both asphaltic concrete (AC) and Portland cement concrete pavement (PCCP) sections may be considered. The pavement sections were designed assuming the following traffic loading and a 20-year design life:

Pavement Traffic Condition Equivalent 18-kip

Single Axle Loadings (ESAL)

Light Duty 40,000

Standard Duty 100,000

Heavy Duty 300,000

The pavement sections recommended below are assumed to bear on compacted on-site soils or upon imported soils with similar or better pavement support qualities. Based on testing of site soils with 5% lime, the pavements bearing on compacted site surface may be designed based on a pavement CBR-value of about 25. Therefore, any imported soils used in the upper 3 feet of fills below pavements should exhibit an R-value of 30 or more.

Based on the subgrade soil and traffic conditions noted above, we recommend the following minimum AC pavement structural sections:

Pavement Traffic Condition

Asphalt Concrete (inches)

Aggregate Base (inches)

Treated Subgrade (inches)

Light Duty 1.5 6 6

Standard Duty 2.5 8 6

Heavy Duty 3 10 6

Hot Mix Asphaltic Concrete Surface Course – The asphaltic concrete surface course should be plant mixed, hot laid Type D (Fine Graded Surface Course) meeting the specifications requirements in TxDOT

2004 Standard Specifications Item 340. Specific criteria for the job specifications should include compaction to within an air void range of 5 to 9 percent calculated using the maximum theoretical gravity mix measured by TxDOT Tex-227-F. The asphalt cement content by percent of total mixture weight should be within ± 0.5 percent asphalt cement from the job mix design.

Base Material – Base material should be composed of crushed limestone, caliche, or crushed concrete meeting the requirements of TxDOT 2004 Standard Specifications Item 247, Type A, B, or D, Grade 1 or 2.

The base material should be compacted to at least 95% of the Modified Effort (ASTM D 1557) maximum dry density at a moisture content within 2% of the optimum moisture content.

Treated Subgrade – The subgrade soils should be treated with Portland cement. The amount of cement should be determined for subgrade soils by conducting laboratory tests on the subgrade once the final

Page 13 of 15 June 6, 2016 subgrade elevation has been established. Based on the classification test results, we recommend that about 5 to 6 percent lime be used for the subgrade soils for estimating and planning. The subgrade should be compacted to a minimum of 95 percent of the Standard Effort (ASTM D 698) maximum dry density at a moisture content between optimum and 3 percent wet of the optimum moisture content. Preferably, traffic, should be kept off the treated subgrade for about 7 days to facilitate curing of the soil-chemical mixture. In addition, the subgrade is not suitable for heavy construction traffic prior to paving.

Based on the subgrade soil and traffic conditions noted above, we recommend the following minimum

PCCP pavement structural sections:

Pavement Traffic Condition

Portland Cement Concrete (inches)

Treated Subgrade (inches)

Light Duty 5 6

Standard Duty 6 6

Heavy Duty 7.5 6

We recommend that waste dumpster areas be constructed of at least 7 inches of reinforced concrete pavement. The concrete pad areas should be designed so that the vehicle wheels of the collection truck are supported on the concrete while the dumpster is being lifted to support the large wheel loading imposed during waste collection.

The pavement design engineer should consider these and other similar situations when planning and designing pavement areas. Waste bin and other areas that are not designed to accommodate these situations often result in localized pavement failures. Presented below are our recommended material requirements for the various pavement sections.

Reinforced Concrete Pavement – The materials and properties of reinforced concrete pavement shall meet applicable requirements in the ACI Manual of Concrete Practice. The Portland cement concrete mix should have a minimum 28-day compressive strength of 3,500 psi.

Reinforcing Steel – Reinforcing steel should consist of the following:

Light Duty: #3 bars spaced at 18 inches or #4 bars spaced at 24 inches on centers in both directions

Standard Duty/Heavy Duty: #3 bars spaced at 12 inches or #4 bars spaced at 18 inches on centers in both directions

Control Joint Spacing – ACI recommendations indicate that control joints should be spaced at about 30 times the thickness of the concrete pavement. Furthermore, ACI recommends a maximum control joint spacing of 12.5 feet for 5-inch thick pavements and a maximum control joint spacing of 15 feet for 6-inch or thicker pavements. Saw cut control joints should be cut within 6 to 12 hours of concrete placement.

Expansion Joint Spacing – ACI recommendations indicate that regularly spaced expansion joints may be deleted from concrete pavements. Therefore, the installation of expansion joints is optional and should be evaluated by the design team.

Page 14 of 15 June 6, 2016

Dowels at Expansion Joints – The dowels at expansion joints, if the joints are provided, should be spaced at 12-inch centers and consist of the following:

Light Duty - 5/8-inch diameter, 12-inch long with 5-inch embedment

Standard Duty - 3/4-inch diameter, 14-inch long with 6-inch embedment

Heavy Duty – 3/4-inch diameter, 14-inch long with 7-inch embedment

Thickened edges should be used along outside edges of concrete pavements. Edge thickness should be at least 2 inches greater than the concrete pavement thickness and taper to the tabulated pavement thickness 36 inches inward from the edge. Integral curbs may be used in lieu of thickened edges.

4.6 Soil Sulfate Concentration & Concrete

Laboratory chemical tests performed on samples of the on-site soils indicated sulfate contents of up to

189 parts per million. Based on the American Concrete Institute (ACI) 318-11 Building Code, the potential for sulfate attack is negligible for water-soluble sulfate contents in soils ranging from 0 percent to 0.10 percent by weight (0 ppm to 1,000 ppm). Therefore, the tested site soils are considered to have a low to moderate potential for sulfate attack, based on ACI criteria. However, we recommend the use of Type II cement for construction of concrete structures in contact with soil at this site. The structural engineer should select the concrete design strength, water-cement ratio, slump at placement, etc., based on the project specific conditions and also based on the recommendations presented in ACI.

4.7 Site Drainage

The ground surface around the edges of structures, flatwork, and pavements should be graded such that water drains rapidly away without ponding. In general, pavement and lawns within five feet of buildings should slope away at gradients of 2 to 5 percent or more. Densely vegetated areas should have minimum gradients of 5 to 10 percent or more away from buildings in the first five feet if practical. Below-slab plumbing should be minimized. The possibility of moisture infiltration beneath a structure, in the event of plumbing leaks, should be considered in the design and construction of underground water and sewer conduits. Roof gutters should be installed on structures. Downspouts should discharge to drainage systems away from structures and flatwork.

Where utility trenches pass under the perimeter wall of any structure, they should be backfilled with either compacted non-pervious fill material (pea gravel or clean sand backfill should be avoided in these areas) or lean concrete, to reduce the potential for the utility trench acting as a conduit for water infiltration into the interior of a building.

4.8 Pre-Construction Conference

We recommend that a pre-construction conference be held. Representatives of the owner, the civil engineer, the geotechnical consultant, and the contractor should be in attendance to discuss the project plans and schedule. Our office should be notified if the project description included herein is incorrect, or if the project characteristics are significantly changed.

Page 15 of 15 June 6, 2016

4.9 Construction Observation and Testing

Since the final design is not complete and final structural loading conditions are not known, we recommend that a general review of the project plans and specifications be conducted before they are finalized to verify that our geotechnical recommendations have been properly interpreted and implemented during design. The recommendations provided in this report are based on the assumption that an adequate program of tests and observations will be conducted during the construction phase in order to evaluate the compliance with our recommendations.

If another geotechnical consultant is selected to perform observation and testing services for the project, we request that the selected consultant provide a letter to the owner, with a copy to RGV Strata, indicating that they fully understand our recommendations and that they are in full agreement with the recommendations contained in this report.

5.0 LIMITATIONS

Some variations in the soil conditions are anticipated between the points explored. The nature and extent of variations may not be evident until construction occurs. If any conditions are encountered at this site that are different from those described in this report, our firm should be immediately notified so that we may make any necessary revisions to the recommendations contained in this report. In addition, if the scope of the proposed construction changes from that described in this report, our firm should also be notified.

The exploration, laboratory testing, and geotechnical analyses presented in this geotechnical report have been conducted in general accordance with current practice and the standard of care exercised by geotechnical consultants performing similar tasks in the project area. No warranty, expressed or implied, is made regarding the conclusions, recommendations, and opinions presented in this report.

This report may be used only by the client and only for the purposes stated within a reasonable time from its issuance, but in no event later than one year from the date of the report. Land or facility use, on and off-site conditions, regulations, or other factors may change over time, and additional work may be required with the passage of time. Similarly, future irrigation, broken water or sewer pipelines, or other factors may adversely influence the project. Any party other than the client who wishes to use this report shall notify RGV Strata of such intended use. RGV Strata may require that additional work be performed and that an updated report be issued. Non- compliance with any of these requirements by the client or anyone else will release RGV Strata from any liability resulting from the use of this report by any unauthorized party and client agrees to defend, indemnify, and hold harmless RGV Strata from any claim or liability associated with such unauthorized use or non-compliance.

APPENDIX A

DIAGRAM IS FOR GENERAL LOCATION ONLY, AND IS NOT INTENDED FOR

CONSTRUCTION PURPOSES

A-1

FIG No.BORING LOCATION PLAN USDA MAB Mexican Fruit Fly

Rearing Facility

Edinburg, Texas

Project No.

Scale:

File Name:

Date:

161021

USDA MAB MFF

April 9, 2016

N/A

--- Boring Location

B-10

B-6

B-7

B-12

B-11

B-13

B-16

B-14B-15

B-18 B-19

B-17

B-20

B-21

B-5

B-4

B-3

B-2

B-1

B-8

B-24

B-32

B-22

B-25

B-26

B-27

B-23

B-28

B-33

B-29

B-31

B-34

B-30

B-9

APPENDIX B

Appendix B April 11, 2016

APPENDIX B

FIELD INVESTIGATION

Soil Borings: Soil borings performed as part of the investigation were extended using a Dietrich Model

D-120 truck mounted drill-rig utilizing 8-inch (OD) diameter hollow-stem auger. During the excavation driven and bulk samples were obtained from selected depths. A field engineer or geologist logged the soil encountered within the borings based on visual inspection of the cuttings and samples and also recorded field penetration test results. Upon completion the borings were backfilled with cuttings derived from auger advancement.

Seismic Methods: Seismic refraction and refraction micro-tremor (ReMi) testing was performed at the site using a 12-channel seismometer and associated geophones. The source for the refraction survey was a sledge hammer and steel striker plate. The ReMi survey uses ambient noise at the site to generate a signal that is then analyzed. Each method generally produces a profile extending approximately 30 feet bgs.

Field Resistivity: Field resistivity surveying was performed using a AGI Mini-Sting resistivity meter. The survey was configured as a Wenner Array with A-spacing ranging between 2 and 50 feet.

N=17

N=10

N=17

CLAYEY SAND (SC)

Medium Dense; Dark Brown to Brown

Boring terminated at 6-feet.

Log of Boring PROJECT: USDA MAB Mexican Fruit Fly Rearing Facility

22675 N. Moorefield Road Edinburg, Texas 78541

BORING NO.: B-1

LAB NO.: 161021

DATE: 3/2/16

CLIENT: International Consulting Engineers SURFACE ELEV.: 216'

Steel Tube Sample

REMARKS:

Split Spoon Sample

Disturbed Sample

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FIELD DATA

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DESCRIPTION OF STRATUM

DRILLING METHOD(S) : Dry auger to boring termination depth.

GROUNDWATER INFORMATION:

Subsurface water was not encountered during drilling operations.

N=17

N=15

N=23

6 25 16 9 42

CLAYEY SAND (SC)

Medium Dense; Brown

Boring terminated at 6-feet.

Log of Boring PROJECT: USDA MAB Mexican Fruit Fly Rearing Facility

22675 N. Moorefield Road Edinburg, Texas 78541

BORING NO.: B-2

LAB NO.: 161021

DATE: 3/2/16

CLIENT: International Consulting Engineers SURFACE ELEV.: 216'

Steel Tube Sample

REMARKS:

Split Spoon Sample

Disturbed Sample

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DRILLING METHOD(S) : Dry auger to boring termination depth.

N=17

N=20

N=27

CLAYEY SAND (SC)

Medium Dense; Dark Brown to Brown

Boring terminated at 6-feet.

Log of Boring PROJECT: USDA MAB Mexican Fruit Fly Rearing Facility

22675 N. Moorefield Road Edinburg, Texas 78541

BORING NO.: B-3

LAB NO.: 161021

DATE: 3/2/16

CLIENT: International Consulting Engineers SURFACE ELEV.: 216'

Steel Tube Sample

REMARKS:

Split Spoon Sample

Disturbed Sample

D E

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DRILLING METHOD(S) : Dry auger to boring termination depth.

N=15

N=16

N=16

6 30 16 14 54

SANDY LEAN CLAY (CL)

Stiff to Very Stiff; Brown

Boring terminated at 6-feet.

Log of Boring PROJECT: USDA MAB Mexican Fruit Fly Rearing Facility

22675 N. Moorefield Road Edinburg, Texas 78541

BORING NO.: B-4

LAB NO.: 161021

DATE: 3/2/16

CLIENT: International Consulting Engineers SURFACE ELEV.: 216'

Steel Tube Sample

REMARKS:

Split Spoon Sample

Disturbed Sample

D E

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FIELD DATA

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L iq u id

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P la st ic ity I n d e x

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DRILLING METHOD(S) : Dry auger to boring termination depth.

N=11

N=18

N=21

CLAYEY SAND (SC)

Medium Dense; Dark Brown

SANDY LEAN CLAY (CL)

Very Stiff; Brown

Boring terminated at 6-feet.

Log of Boring PROJECT: USDA MAB Mexican Fruit Fly Rearing Facility

22675 N. Moorefield Road Edinburg, Texas 78541

BORING NO.: B-5

LAB NO.: 161021

DATE: 3/2/16

CLIENT: International Consulting Engineers SURFACE ELEV.: 216'

Steel Tube Sample

REMARKS:

Split Spoon Sample

Disturbed Sample

D E

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FIELD DATA

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DRILLING METHOD(S) : Dry auger to boring termination depth.

N=16

N=32

N=58

7 29 17 12 48

CLAYEY SAND (SC)

Medium Dense to Very Dense; Brown

Boring terminated at 6-feet.

Log of Boring PROJECT: USDA MAB Mexican Fruit Fly Rearing Facility

22675 N. Moorefield Road Edinburg, Texas 78541

BORING NO.: B-6

LAB NO.: 161021

DATE: 3/2/16

CLIENT: International Consulting Engineers SURFACE ELEV.: 216'

Steel Tube Sample

REMARKS:

Split Spoon Sample

Disturbed Sample

D E

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F E

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FIELD DATA

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DRILLING METHOD(S) : Dry auger to boring termination depth.

N=7

N=13

N=16

CLAYEY SAND (SC)

Loose to Medium Dense; Brown

Boring terminated at 6-feet.

Log of Boring PROJECT: USDA MAB Mexican Fruit Fly Rearing Facility

22675 N. Moorefield Road Edinburg, Texas 78541

BORING NO.: B-7

LAB NO.: 161021

DATE: 3/2/16

CLIENT: International Consulting Engineers SURFACE ELEV.: 216'

Steel Tube Sample

REMARKS:

Split Spoon Sample

Disturbed Sample

D E

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H

F E

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FIELD DATA

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L iq u id

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DRILLING METHOD(S) : Dry auger to boring termination depth.

N=12

N=6

N=8

9 25 17 8 42

CLAYEY SAND (CL)

Medium Dense to Loose; Dark Brown to Brown

Boring terminated at 6-feet.

Log of Boring PROJECT: USDA MAB Mexican Fruit Fly Rearing Facility

22675 N.