ESBD24302262026_Attachment B - Geotechnical Report-IFB 2026-B02.pdf

GEOTECHNICAL ENGINEERING STUDY

FOR

BEAR CREEK PASS LOWWATER CROSSING

BEAR CREEK PASS

HAYS COUNTY, TEXAS

O:\Closed Projects\Austin\2017\AAA17-099-00 Bear Creek Pass Low Water Bridge Crossing\Reporting\REVISED Report\AAA17-099-00 Report-Revised.docx

GEO100 AUS 01/14/2020

Project No. AAA17 099 00 REVISED August 26, 2020

Mr. Craig Wilson, P.E.

M&S Engineering 376 Landa Street New Braunfels, TX 78130

RE: Geotechnical Engineering Study Bear Creek Pass LowWater Crossing Bear Creek Pass Hays County, Texas

Dear Mr. Wilson:

RABA KISTNER Consultants Inc. (RKCI) is pleased to submit this report of our Geotechnical Engineering Study for the above referenced project. We understand that the type of crossing has changed from a bridge crossing to a box culvert crossing since we prepared our proposal (RKCI Proposal No. PAA17 125 00), dated August 16, 2017. Our services were revised to reflect the box culvert crossing being considered.

The purpose of this study was to drill 2 borings, to perform laboratory testing to classify and characterize subsurface conditions, and to prepare an engineering report presenting design and construction recommendations for the proposed culvert crossing, as well as to evaluate soil conditions for support of pavements.

The following report contains our design recommendations and considerations based on our current understanding of information provided to us at the time of this study. There may be alternatives for value engineering of the foundation and pavement systems. RKCI recommends that a meeting be held with the Owner and design team to evaluate if alternatives are available.

We appreciate the opportunity to be of service to you on this project. Should you have any questions about the information presented in this report, or if we may be of additional assistance with value engineering or on the materials testing quality control program during construction, please call.

Very truly yours, RABA KISTNER CONSULTANTS, INC.

Reed S. Kistler, P.E. 08/26/2020 Yvonne Garcia Thomas, P.E.

Project Engineer Vice President

RSK/YGT: JG

Attachments Copies Submitted: Above (1 Electronic)

CONSULTANTS • ENVIRONMENTAL • PROJECT MANAGEMENT • INFRASTRUCTURE

8100 Cameron Road, Suite B-150 Austin, TX 78754

P 512.339.1745 F 512.339.6174 TBPE Firm F-3257

WWW.RKCI.COM

GEOTECHNICAL ENGINEERING STUDY

For

BEAR CREEK PASS LOWWATER CROSSING

BEAR CREEK PASS

HAYS COUNTY, TEXAS

Prepared for

M&S ENGINEERING

New Braunfels, Texas

Prepared by

RABA KISTNER CONSULTANTS, INC.

Austin, Texas

PROJECT NO. AAA17 099 00

August 26, 2020

Project No. AAA17 099 00 July 2, 2020

TABLE OF CONTENTS

i

INTRODUCTION

PROJECT DESCRIPTION

LIMITATIONS

BORINGS AND LABORATORY TESTS

SCOUR ANALYSIS

GENERAL SITE CONDITIONS

SITE DESCRIPTION

GEOLOGY

STRATIGRAPHY

GROUNDWATER

FOUNDATION ANALYSIS

EXPANSIVE SOIL RELATED MOVEMENTS

BOX CULVERT RECOMMENDATIONS

ALLOWABLE BEARING PRESSURE

LATERAL EARTH PRESSURES

BACKFILL COMPACTION

DRAINAGE

SCOUR AND EROSION PROTECTION

BOX CULVERT CONSTRUCTION CONSIDERATIONS

SITE PREPARATION

EMBANKMENT FILL

Type C Material

ON SITE ROCK FILL

CEMENT TREATED SUBGRADE

FOUNDATION EXCAVATIONS

BACKFILL BENCHING

EXCAVATION EQUIPMENT

PAVEMENT CONSIDERATIONS

CONSTRUCTION RELATED SERVICES

CONSTRUCTION MATERIALS TESTING AND OBSERVATION SERVICES

BUDGETING FOR CONSTRUCTION TESTING

Project No. AAA17 099 00 REVISED August 26, 2020

ATTACHMENTS

ii

The following figures are attached and complete this report:

Boring Location Map.......................................................................................................................... Figure 1 Logs of Borings .......................................................................................................................... Attachment A Grain Size Curve ........................................................................................................................ Attachment B Important Information About Your Geotechnical Engineering Report

INTRODUCTION

RABA KISTNER Consultants Inc. (RKCI) has completed the authorized subsurface exploration and foundation analysis for the culvert crossing to be located along Bear Creek Pass in Hays County, Texas. This report briefly describes the procedures utilized during this study and presents our findings along with our recommendations for foundation design and construction considerations, as well as for pavement design and construction guidelines.

PROJECT DESCRIPTION

The improvements being considered in this study include a box culvert crossing for Bear Creek Pass spanning Bear Creek located in Hays County, Texas. It is our understanding that the crossing will require eight 9 by 7 ft box culverts to span Bear Creek. The top of the crossing will be around elevation 887 ft and the base elevation of Bear Creek is around elevation 878 ft. We understand the base of the culverts will be around elevation 878 ft. Fills and cuts will likely be required to install the culverts and construct the approaches. Likewise, we assume the box culverts will be installed by open cut excavation methods.

LIMITATIONS

This engineering report has been prepared in accordance with accepted Geotechnical Engineering practices in the region of central Texas and for the use of M&S Engineering (Client) and its representatives for design purposes. This report may not contain sufficient information for purposes of other parties or other uses. This report is not intended for use in determining construction means and methods. The attachments and report text should not be used separately.

The recommendations submitted in this report are based on the data obtained from 2 borings drilled at this site, our understanding of the project information provided to us, and the assumption that site grading will result in only minor changes in the existing topography. If the project information described in this report is incorrect, is altered, or if new information is available, we should be retained to review and modify our recommendations.

This report may not reflect the actual variations of the subsurface conditions across the site. The nature and extent of variations across the site may not become evident until construction commences. The construction process itself may also alter subsurface conditions. If variations appear evident at the time of construction, it may be necessary to reevaluate our recommendations after performing on site observations and tests to establish the engineering impact of the variations.

The scope of our Geotechnical Engineering Study does not include an environmental assessment of the air, soil, rock, or water conditions either on or adjacent to the site. No environmental opinions are presented in this report.

If elevations differ from those discussed in this report by more than plus or minus 1 ft, our office should be informed about these changes. If needed and/or if desired, we will reexamine our analyses and make supplemental recommendations.

BORINGS AND LABORATORY TESTS

Subsurface conditions at the site were evaluated by drilling 2 borings (B 1 and B 2) using a truck mounted drilling rig at the locations shown on the Boring Location Map, Figure 1. Borings were located on each side of Bear Creek and the locations were documented in the field utilizing a hand held GPS device. Borings B 1 and B 2 were drilled to approximate depths of 25 and 35 ft below the existing ground surface, respectively; penetrating 20 ft into limestone. During drilling operations, the following samples were collected:

Type of Sample Number Collected

Split Spoon (with 170 lb hammer) 7

Texas Cone Penetrometer (Tex 132 E) 12

NX Rock Core 35 ft

Each sample was visually classified in the laboratory by a member of our geotechnical engineering staff.

The geotechnical engineering properties of the strata were evaluated by the following tests:

Type of Test Number Conducted

Natural Moisture Content (Tex 103 E) 6

Atterberg Limits (Tex 104 E, Tex 105 E, Tex 106 E) 3

No. 200 Sieve Wash (Tex 111 E) 1

Sieve Analysis (Tex 110 E) – “Scour” sample 1

The results of all laboratory tests are presented in numerical form on the WinCore boring logs provided in Attachment A. The results of the sieve analysis have been plotted on the attached Grain Size Curve provided in Attachment B.

Texas Cone Penetrometer (TCP) test results are noted as “blows per foot” on the boring log (divided into 6 in. increments) where “blows per ft” refers to the number of blows required to drive a conical driving point 1 ft into soil/weak rock with a falling, 170 lb hammer following seating blows equal to the lesser of 12 blows and 6 inches of penetration. Where hard or dense materials were encountered, each increment was terminated at 50 blows even if 6 in. of penetration had not been achieved in that increment.

The core recovery (REC) presented on the logs is the total length of the recovered material divided by the attempted run length during coring activities, presented as a percentage. The Rock Quality Designation (RQD) is the sum of the length of all recovered rock segments measuring 4 inches or more divided by the attempted run length during coring activities, presented as a percentage.

Samples will be retained in our laboratory for 30 days after submittal of this report. Other arrangements may be provided at the request of the Client.

SCOUR ANALYSIS

A sieve analysis was performed of a bulk sample collected at the south bank of Bear Creek to assist in determining scour potential. The D90 and D50 grain sizes are shown in the table below and the complete sieve analysis results are shown on the Grain Size Curve in Attachment B.

D90 (mm) D50 (mm)

12.22 0.14

GENERAL SITE CONDITIONS

SITE DESCRIPTION

The project site is located approximately 0.4 miles south of the intersection of FM 1826 and Bear Creek Pass in Hays County, Texas. The crossing at Bear Creek is currently a low water crossing. The topography in the vicinity of the crossing generally slopes downward toward Bear Creek.

GEOLOGY

A review of the Geologic Atlas of Texas, Austin Sheet, indicates that this site is naturally underlain with the soils/rocks of the Glen Rose formation. The Glen Rose formation in generally characterized as limestone, dolomite and marl as alternating resistant and recessive beds that form a stair step topography. The limestone is generally fine grained andmarly. The dolomite is also fine grained, porous and fossiliferous. The Glen Rose formation is divided into and upper and a lower part with the upper part being relatively thinner bedded, more dolomitic and less fossiliferous. The lower part being more massive in nature. Key geotechnical engineering concerns for development supported on this formation are the porous zones and the hardness of the limestone as it impacts excavation operations.

STRATIGRAPHY

The subsurface conditions encountered at the boring locations are shown on the WinCore boring logs, in Attachment A. These boring logs represent our interpretation of the subsurface conditions based on the field logs, visual examination of field samples by our personnel, and test results of selected field samples.

Each stratum has been designated by grouping soils that possess similar physical and engineering characteristics. The lines designating the interfaces between strata on the boring logs represent approximate boundaries. Transitions between strata may be gradual.

In general, soil conditions consist of sandy alluvium and clay overlying hard to very hard limestone. The alluvium was encountered in boring B 2 to a depth of approximately 8 ft below the existing ground surface.

Limestone was encountered in borings B 1 and B 2 at approximately 3 and 14 ft below the existing ground surface, respectively. The limestone is moderately weathered and intensely to moderately fractured to the depths explored. REC and RQD of the cored limestone ranged from 100 to 33 percent and 67 to 0 percent, respectively.

GROUNDWATER

Groundwater seepagewas observed in both borings, near the clay/limestone interface and near the sandy layers. Groundwater conditions in the vicinity of the creek will be influenced by the water level of the creek. Additionally, fluctuations in groundwater levels occur due to variation in rainfall and surface water run off. The construction process itself may also cause variations in the groundwater level.

Boring Depth to Groundwater Seepage During Drilling*

(ft)

Depth to Groundwater Upon Completion of Drilling*

(ft)

B 1 2.2 2.2

B 2 12.5 12.5 *Depth below the existing ground surface at the time of our study

FOUNDATION ANALYSIS

EXPANSIVE SOIL RELATED MOVEMENTS

The anticipated groundmovements due to swelling of the underlying soils at the site were estimated using the empirical procedure, Texas Department of Transportation (TxDOT) Tex 124 E, Method for Determining the Potential Vertical Rise (PVR). A PVR value less than 1 in. was estimated for the stratigraphic conditions encountered in our borings. A surcharge load of 1 psi (concrete slab and sand layer), an active zone extending to the depth of the soil/limestone interface, and dry moisture conditions were assumed in estimating the above PVR values.

BOX CULVERT RECOMMENDATIONS

Based on the results of our field and laboratory studies, and our analysis, it is our opinion the proposed box culvert crossing can be constructed at the site. The following sections provide design allowable bearing pressure and lateral earth pressure recommendations for use in design of the box culvert crossing.

ALLOWABLE BEARING PRESSURE

Based on provided information, we assume the culverts will be installed at an invert elevation equal to or below the current base elevation of Bear Creek. The bearing strata at this elevation will likely consist of limestone. Culvert wing wall footings founded on limestone or on lean concrete overlying limestone should be proportioned using the design parameters tabulated below. Footings should be protected from undermining.

Minimum depth below final grade and depth of scour 12 in.

Maximum allowable bearing pressure for footings (limestone) 8,000 psf

Coefficient of sliding friction (limestone) 0.7

Available Passive Resistance1 (limestone) 800 pcf 1 Depth of scour and additional 1 ft below scour depth should be neglected for evaluating passive resistance.

Modeled as an equivalent fluid pressure.

The above presented maximum allowable bearing pressures will provide a calculated factor of safety of about 3 with respect to the measured shear strength. The allowable bearing pressure is a net bearing pressure and applies to the total of dead and long term live loads and may be increased by 1/3 when considering short term loading such as wind and flood loads.

LATERAL EARTH PRESSURES

Equivalent fluid density values for computation of lateral soil pressures acting on retaining walls were evaluated for various types of backfill materials that may be placed behind the retaining walls. These values, are presented below in preferential order for use as backfill materials. At rest earth pressures should be used for the box culvert sidewalls and headwalls, while active earth pressures should be used for the wing walls. We assume backfill material placed behind the wall will extend at least at a 1H:1V (Horizontal: Vertical) projection from the base of the wall.

Backfill Type

Estimated Total Unit Weight (pcf)

Active Condition At Rest Condition

Equivalent Fluid Density ABOVE Water Table

(pcf)

Equivalent Fluid Density BELOW Water Table

(pcf)1

Equivalent Fluid Density ABOVE Water Table

(pcf)

Equivalent Fluid Density BELOW Water Table

(pcf)1

Washed Gravel 135 40 21 60 33

Crushed Limestone 145 35 20 55 32

Clean Sand 120 40 19 60 29

Pit Run Clayey Gravels or Sands 135 45 23 65 35

Clays 120 70 Not Recommended

90 Not Recommended

1. Does not include hydrostatic pressure.

The values presented above assume the surface of the backfill materials to be level. Sloping the surface of the backfill materials will increase the surcharge load acting on the structures. The above values also do not include the effect of surcharge loads such as construction equipment, vehicular loads, or future storage near the structures. As discussed later, the walls should be provided with a drain system to allow for the dissipation of water. Surcharge loads and groundwater pressures should be considered in designing any structures subjected to lateral pressures.

BACKFILL COMPACTION

Placement and compaction of backfill will be critical, particularly at locations where backfill will support adjacent pavements and other flatwork. If the backfill is not properly compacted in these areas, the adjacent areas can be subject to settlement.

To reduce potential settlement of adjacent foundations/flatwork, the backfill materials should be placed and compacted as recommended in the Embankment Fill section of this report. Each lift or layer of the backfill should be tested during the backfilling operations to document the degree of compaction. Within at least a 5 ft zone of the wall backside, we recommend that compaction be accomplished using hand guided compaction equipment capable of achieving the maximum density in a series of 3 to 5 passes.

DRAINAGE

Backfill placed below the 100 year flood elevation of the creek should consist of backfill material having less than 5 percent passing the No. 200 sieve. Additionally, we recommend the use of a drain trench and pipe. The drain pipe should consist of a slotted, heavy duty, corrugated polyethylene pipe and should be installed and bedded according to the manufacturer’s recommendations. The drain trench should extend a minimum of 12 in. behind the back face of the wall and should be filled with gravel (meeting the requirements of ASTM D 448 coarse concrete aggregate Size No. 57 or 67) and extend from the base of the structure to within 2 ft of the top of the structure. The bottom of the drain trench will provide an envelope of gravel around the pipe with minimum dimensions consistent with the pipe manufacturer’s recommendations. The gravel should be wrapped with a suitable geotextile fabric (such as Mirafi 140N or equivalent) to help reduce the intrusion of fine grained soil particles into the drain system. The pipe should be sloped and equipped with clean out access fittings consistent with state of the practice plumbing procedures.

As an alternative to a full height gravel drain trench behind the proposed structures, consideration may be given to utilizing a manufactured geosynthetic material for wall drainage. A number of products are available to control hydrostatic pressures acting on earth retaining structures, including Amerdrain (manufactured by American Wick Drain Corp.), Miradrain (manufactured by Mirafi, Inc.), Enkadrain (manufactured by American Enka Company), and Geotech Insulated Drainage Panel (manufactured by Geotech Systems Corp.). The geosynthetics are placed directly against the retaining structures and are hydraulically connected to the gravel envelope located at the base of the structures.

Weepholes may be provided along the length of the proposed structures, if desired, in addition to one of the two alternative drainage measures presented above. Based on our experience, weepholes, as the only drainage measure, often become clogged with time and do not provide the required level of drainage from behind structures. We recommend that RKCI review the final drainage design before construction.

SCOUR AND EROSION PROTECTION

Special precautions should be taken with regards to foundations in or near flowing water. Sandy soils, such as those encountered in our soil borings, are susceptible to undermining and soil erosion along the base of the structure. The soils above the limestone encountered in our borings are considered erodible materials and consideration should be given for the following, if present:

Placement of concrete rip rap or boulder fills to provide embankment armoring protection immediately adjacent to the base of the retaining wall and at least 5 ft outward from the front of the wall.

Placement of concrete rip rap to be installed over the granular backfill materials of the retaining wall and extending a distance beyond the retained embankment to protect the retained embankment from experiencing erosion if the creek storm waters crest above the retaining wall.

Constructing the improved subgrade fill using cement treated material. These material will be less prone to infiltration, resistant to potential scouring and undermining, and provide significant bearing improvements to support the retaining wall.

BOX CULVERT CONSTRUCTION CONSIDERATIONS

SITE PREPARATION

All areas to support fills should be stripped of all vegetation and organic topsoil. Tree roots greater than 1 inch in diameter should be grubbed and removed. Any voids resulting from removal of limestone boulders or tree roots should be backfilled with a suitable, compacted fill material, free of organics, degradable material, and particles exceeding 4 inches in size.

Exposed subgrades should be thoroughly proofrolled in order to locate weak, compressible zones. A minimum of 5 passes of a fully loaded dump truck or a similar heavily loaded piece of construction equipment should be used for planning purposes. Proofrolling operations should be observed by the Geotechnical Engineer or their representative to document subgrade condition and preparation. Weak or soft areas identified during proofrolling should be removed and replaced with suitable, compacted on site clays, free of organics, oversized materials, and degradable or deleterious materials.

Upon completion of the proofrolling operations and just prior to fill placement or culvert installation, the exposed subgrade, if consisting of soil, should be moisture conditioned by scarifying to a minimum depth of 6 in. and recompacting to a minimum of 95 percent of the maximum density determined from TxDOT, Tex 114 E, Compaction Test. The moisture content of the subgrade should be maintained within the range of optimum moisture content to 3 percentage points above optimum moisture content until permanently covered.

EMBANKMENT FILL

Materials used as borrow fill for final site grading preferably shall consist of the following as indicated in the plans:

2014 TxDOT Item 132, Type A granular fill; or 2014 TxDOT Item 132, Type C on site material.

Type C Material

Materials classified in accordance with the Unified Soil Classification System (USCS) as clayey sand (SC) or sandy lean clay (CL) may be considered satisfactory for use as Type C embankment fill along the roadway alignment. Roadway embankment fill materials shall have a maximum liquid limit not exceeding 40, a plasticity index between 7 and 20, and amaximum particle size not exceeding 4 inches or one half the loose lift thickness, whichever is smaller. In addition, if these materials are utilized, grain size analyses and Atterberg Limits must be performed during placement at a rate of one test each per 5,000 cubic yards of material due to the high degree of variability associated with pit run materials.

Roadway embankment fill should be placed in accordance with TxDOT Item 132, “Embankment” and Item 400, “Excavation and Backfill for Structures”. Materials should be compacted to a minimum of 95 percent of the maximum density determined from the Texas Department of Transportation Compaction Test (TxDOT, Tex 113 E or Tex 114 E). Themoisture content of the fill should be maintained within the range of optimum moisture content to 3 percentage points above optimumuntil permanently covered or the next lift is placed.

If the above listed alternative materials are being considered for bidding purposes, the materials should be submitted to the Geotechnical Engineer for pre approval at a minimum of 10 working days or more prior to the bid date. Failure to do so will be the responsibility of the contractor. The contractor will also be responsible for ensuring that the properties of all delivered alternate fill materials are similar to those of the pre approved submittal. It should also be noted that when using alternative fill materials, difficulties may be experienced with respect to moisture control during and subsequent to fill placement, as well as with erosion, particularly when exposed to inclement weather. This may result in sloughing of trenches and/or pumping of the fill materials.

ON SITE ROCK FILL

If excavations extend to significant depths into the limestone formation, consideration can be given to utilizing the excavated limestone for embankment fill. However, processing of the excavated material will be required to reduce the maximum particle size to 4 in. Furthermore, special care will be required during excavation activities to separate organics and any plastic clay seams encountered. In addition, the processed material must meet the specifications given above for TxDOT Item 132 materials. If on site materials cannot be processed to meet the required criteria, imported embankment fill materials should be utilized.

CEMENT TREATED SUBGRADE

Cement treated embankment fills shall be installed in accordance with 2014 TxDOT Standard Specifications, Item 132, Embankment. The materials shall consist of Type A Granular fill mixed with hydraulic cement in accordance to Item 275. Using the materials proposed for the project, the Engineer will determine the target cement content and optimummoisture content necessary to produce a stabilized mixture meeting the strength requirement. Unless indicated in the plans, we recommend a 7 day compressive strength requirement of 300 psi.

Cement treated subgrade soils should be compacted to aminimum of 95 percent of the maximum density at a moisture content within the range of optimum moisture content to 3 percentage points above the optimum moisture content as determined by Tex 113 E.

FOUNDATION EXCAVATIONS

Foundation excavations should be observed by the Geotechnical Engineer or their representative prior to placement of box culverts. This is necessary to observe that the bearing soils at the bottom of the excavations are similar to those encountered in our boring and that excessive loose materials and water are not present in the excavations. If soft pockets of soil are encountered in the foundation excavations, they should be removed and replaced with lean concrete up to the design foundation bearing elevations.

We recommend foundation excavations occur when the creek is dry. Dewatering will be required if excavations extend below the water level of the creek or if groundwater seepage is encountered within the foundation excavations. It is the contractor’s responsibility to select the dewatering methods.

However, depending on the magnitude of water present within the excavation and water level of the creek, the utilization of sumps and pumps alone may not be enough to control the water and additional water control measures should be considered.

BACKFILL BENCHING

Level benches should be cut into the existing sloping faces for preparation of backfill placement. The benches should be a minimum of 10 feet wide or 1 ½ times the width of the compaction equipment, whichever is wider.

EXCAVATION EQUIPMENT

Due to the shallow nature of the surficial soils, excavations at this site will require removal of the underlying rock formation. Rock may also be encountered at the surface in some areas of this site. Thus, the need of rock excavation equipment should be anticipated for construction at this site. Our boring logs are not intended for use in determining construction means and methods and may therefore be misleading if used for that purpose. We recommend that earth work and utility contractors interested in bidding on the work perform their own tests in the form of test pits to determine the quantities of the different materials to be excavated, as well as the preferred excavation methods and equipment for this site.

PAVEMENT CONSIDERATIONS

We understand the Hays County minimum pavement sections will be used for the culvert crossing. The results of our field study and laboratory testing, indicate the near surface soils consist of relatively low PI material (less than 25). Therefore, provided the backfill and fill used for the culvert construction is also of relatively low PI material, it is our opinion the minimum pavement section for the functional classification of Bear Creek Pass should be satisfactory.

CONSTRUCTION RELATED SERVICES

CONSTRUCTION MATERIALS TESTING AND OBSERVATION SERVICES

As presented in the attachment to this report, Important Information About Your Geotechnical Engineering Report, subsurface conditions can vary across a project site. The conditions described in this report are based on interpolations derived froma limited number of data points. Variations will be encountered during construction, and only the geotechnical design engineer will be able to determine if these conditions are different than those assumed for design.

Construction problems resulting from variations or anomalies in subsurface conditions are among the most prevalent on construction projects and often lead to delays, changes, cost overruns, and disputes. These variations and anomalies can best be addressed if the geotechnical engineer of record, RKCI is retained to perform construction observation and testing services during the construction of the project. This is because:

RKCI has an intimate understanding of the geotechnical engineering report’s findings and recommendations. RKCI understands how the report should be interpreted and can provide such interpretations on site, on the client’s behalf.

RKCI knows what subsurface conditions are anticipated at the site.

RKCI is familiar with the goals of the owner and project design professionals, having worked with them in the development of the geotechnical workscope. This enables RKCI to suggest remedial measures (when needed) which help meet the owner’s and the design teams’ requirements.

RKCI has a vested interest in client satisfaction, and thus assigns qualified personnel whose principal concern is client satisfaction. This concern is exhibited by the manner in which contractors’ work is tested, evaluated and reported, and in selection of alternative approaches when such may become necessary.

RKCI cannot be held accountable for problems which result due to misinterpretation of our findings or recommendations whenwe are not on hand to provide the interpretationwhich is required.

BUDGETING FOR CONSTRUCTION TESTING

Appropriate budgets need to be developed for the required construction testing and observation activities.

At the appropriate time before construction, we advise that RKCI and the project designers meet and jointly develop the testing budgets, as well as review the testing specifications as it pertains to this project.

Once the construction testing budget and scope of work are finalized, we encourage a preconstruction meeting with the selected contractor to review the scope of work to make sure it is consistent with the construction means and methods proposed by the contractor. RKCI looks forward to the opportunity to provide continued support on this project, and would welcome the opportunity to meet with the Project Team to develop both a scope and budget for these services.

ATTACHMENTS

B ea r C re ek

B-2

B-1

BORING LOCATION MAP

BEAR CREEK PASS LOW WATER CROSSING

BEAR CREEK PASS

HAYS COUNTY, TEXAS

PROJECT No.:

AAA17-099-00

DRAWN BY:

ISSUE DATE:

REVIEWED BY:

CHECKED BY:

JMR

06/25/2020

YGT

RTS

NOTE: This Drawing is Provided for Illustration Only, May Not be to Scale and is Not Suitable for Design or Construction Purposes μ

Austin

£¤290 UV1

Hays

Travis

SITE LOCATION MAP

S I T E

FIGURE

1HAYS

COUNTY

TBPE Firm Number 3257

8100 Cameron Road, Suite B-150 Austin, Texas 78754

(512)339-1745 TEL

(512)339-6174 FAX

www.rkci.com

0 50 10025

FEET

1 INCH = 100 FEET

LEGEND

!? BORING

SOURCE: Aerial imagery from Google Earth Pro - 2019

ATTACHMENT A

WINCORE BORING LOGS

ATTACHMENT B

GRAIN SIZE CURVE

C la ye y

SA

N

D w ith g ra ve l (

SC

Geotechnical-Engineering Report

Geotechnical Services Are Performed for Specific Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the specific needs of their clients. A geotechnical-engineering study conducted for a civil engineer may not fulfill the needs of a constructor — a construction contractor — or even another civil engineer. Because each geotechnical- engineering study is unique, each geotechnical-engineering report is unique, prepared solely for the client. No one except you should rely on this geotechnical-engineering report without first conferring with the geotechnical engineer who prepared it. And no one

— not even you — should apply this report for any purpose or project except the one originally contemplated.

Read the Full Report Serious problems have occurred because those relying on a geotechnical-engineering report did not read it all. Do not rely on an executive summary. Do not read selected elements only.

Geotechnical Engineers Base Each Report on a Unique Set of Project-Specific Factors Geotechnical engineers consider many unique, project-specific factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk-management preferences; the general nature of the structure involved, its size, and configuration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engineer who conducted the study specifically indicates otherwise, do not rely on a geotechnical-engineering report that was:

• not prepared for you;

• not prepared for your project;

• not prepared for the specific site explored; or

• completed before important project changes were made.

Typical changes that can erode the reliability of an existing geotechnical-engineering report include those that affect:

• the function of the proposed structure, as when it’s changed from a parking garage to an office building, or from a light-industrial plant to a refrigerated warehouse;

• the elevation, configuration, location, orientation, or weight of the proposed structure;

• the composition of the design team; or

• project ownership.

As a general rule, always inform your geotechnical engineer of project changes—even minor ones—and request an assessment of their impact. Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed.

Subsurface Conditions Can Change A geotechnical-engineering report is based on conditions that existed at the time the geotechnical engineer performed the study. Do not rely on a geotechnical-engineering report whose adequacy may have been affected by: the passage of time;

man-made events, such as construction on or adjacent to the site; or natural events, such as floods, droughts, earthquakes, or groundwater fluctuations. Contact the geotechnical engineer before applying this report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems.

Most Geotechnical Findings Are Professional Opinions Site exploration identifies subsurface conditions only at those points where subsurface tests are conducted or samples are taken. Geotechnical engineers review field and laboratory data and then apply their professional judgment to render an opinion about subsurface conditions throughout the site. Actual subsurface conditions may differ — sometimes significantly — from those indicated in your report. Retaining the geotechnical engineer who developed your report to provide geotechnical-construction observation is the most effective method of managing the risks associated with unanticipated conditions.

A Report’s Recommendations Are Not Final Do not overrely on the confirmation-dependent recommendations included in your report. Confirmation-dependent recommendations are not final, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can finalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engineer who developed your report cannot assume responsibility or liability for the report’s confirmation-dependent recommendations if that engineer does not perform the geotechnical-construction observation required to confirm the recommendations’ applicability.

A Geotechnical-Engineering Report Is Subject to Misinterpretation Other design-team members’ misinterpretation of geotechnical-engineering reports has resulted in costly

Important Information about This

Subsurface problems are a principal cause of construction delays, cost overruns, claims, and disputes.

While you cannot eliminate all such risks, you can manage them. The following information is provided to help.

problems. Confront that risk by having your geo technical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and specifications. Constructors can also misinterpret a geotechnical-engineering report. Confront that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing geotechnical construction observation.

Do Not Redraw the Engineer’s Logs Geotechnical engineers prepare final boring and testing logs based upon their interpretation of field logs and laboratory data. To prevent errors or omissions, the logs included in a geotechnical-engineering report should never be redrawn for inclusion in architectural or other design drawings. Only photographic or electronic reproduction is acceptable, but recognize that separating logs from the report can elevate risk.

Give Constructors a Complete Report and Guidance Some owners and design professionals mistakenly believe they can make constructors liable for unanticipated subsurface conditions by limiting what they provide for bid preparation.

To help prevent costly problems, give constructors the complete geotechnical-engineering report, but preface it with a clearly written letter of transmittal. In that letter, advise constructors that the report was not prepared for purposes of bid development and that the report’s accuracy is limited;

encourage them to confer with the geotechnical engineer who prepared the report (a modest fee may be required) and/ or to conduct additional study to obtain the specific types of information they need or prefer. A prebid conference can also be valuable. Be sure constructors have sufficient time to perform additional study. Only then might you be in a position to give constructors the best information available to you, while requiring them to at least share some of the financial responsibilities stemming from unanticipated conditions.

Read Responsibility Provisions Closely Some clients, design professionals, and constructors fail to recognize that geotechnical engineering is far less exact than other engineering disciplines. This lack of understanding has created unrealistic expectations that have led to disappointments, claims, and disputes. To help reduce the risk of such outcomes, geotechnical engineers commonly include a variety of explanatory provisions in their reports. Sometimes labeled “limitations,” many of these provisions indicate where geotechnical engineers’ responsibilities begin and end, to help others recognize their own responsibilities and risks. Read these provisions closely. Ask questions. Your geotechnical engineer should respond fully and frankly.

Environmental Concerns Are Not Covered The equipment, techniques, and personnel used to perform an environmental study differ significantly from those used to perform a geotechnical study. For that reason, a geotechnical-engineering report does not usually relate any environmental findings, conclusions, or recommendations; e.g., about the likelihood of encountering underground storage tanks or regulated contaminants. Unanticipated environmental problems have led to numerous project failures. If you have not yet obtained your own environmental information, ask your geotechnical consultant for risk-management guidance. Do not rely on an environmental report prepared for someone else.

Obtain Professional Assistance To Deal with Mold Diverse strategies can be applied during building design, construction, operation, and maintenance to prevent significant amounts of mold from growing on indoor surfaces.

To be effective, all such strategies should be devised for the express purpose of mold prevention, integrated into a comprehensive plan, and executed with diligent oversight by a professional mold-prevention consultant. Because just a small amount of water or moisture can lead to the development of severe mold infestations, many mold- prevention strategies focus on keeping building surfaces dry. While groundwater, water infiltration, and similar issues may have been addressed as part of the geotechnical- engineering study whose findings are conveyed in this report, the geotechnical engineer in charge of this project is not a mold prevention consultant;

none of the services performed in connection with the geotechnical engineer’s study were designed or conducted for the purpose of mold prevention. Proper implementation of the recommendations conveyed in this report will not of itself be sufficient to prevent mold from growing in or on the structure involved.

Rely, on Your GBC-Member Geotechnical Engineer for Additional Assistance Membership in the Geotechnical Business Council of the Geoprofessional Business Association exposes geotechnical engineers to a wide array of risk-confrontation techniques that can be of genuine benefit for everyone involved with a construction project. Confer with you GBC-Member geotechnical engineer for more information.

8811 Colesville Road/Suite G106, Silver Spring, MD 20910 Telephone: 301/565-2733 Facsimile: 301/589-2017 e-mail: info@geoprofessional.org www.geoprofessional.org

Copyright 2015 by Geoprofessional Business Association (GBA). Duplication, reproduction, or copying of this document, or its contents, in whole or in part, by any means whatsoever, is strictly prohibited, except with GBA’s specific written permission. Excerpting, quoting, or otherwise extracting wording from this document is permitted only with the express written permission of GBA, and only for purposes of scholarly research or book review. Only members of GBA may use this document as a complement to or as an element of a geotechnical-engineering report. Any other firm, individual, or other entity that so uses this document without being a GBA member could be commiting negligent or intentional (fraudulent) misrepresentation.

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