Geotechnical_Report-SH_105_West_Gravity_Sewer_Upgrade-25-S-274.pdf

GEOTECHNICAL INVESTIGATION REPORT

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

LASALLE TO HIGHLAND HOLLOW

CONROE, TEXAS

PREPARED FOR:

City of Conroe

700 Metcalf Street

Conroe TX, 77301

PREPARED BY:

HTS, Inc. Consultants

416 Pickering Street

Houston, Texas 77091-3312

HTS Project No.: 25-S-274

September 4, 2025

Excellence in Engineering, Consulting, Testing and Inspection

September 4, 2025

City of Conroe

700 Metcalf Street

Conroe TX, 77301

Attn: Ms. Jennifer Gilmore

Engineering Projects Coordinator

Re: Geotechnical Investigation Report

Proposed SH-105 West Gravity Sewer Upgrade

LaSalle to Highland Hollow

Conroe, Texas

HTS Project No.: 25-S-274

Dear Ms. Gilmore:

HTS, Inc. Consultants is pleased to transmit this report of the geotechnical investigation for the above referenced project. This report includes the results of field and laboratory testing, geotechnical design parameters, and recommendations pertaining to the proposed development.

We appreciate the opportunity to perform this geotechnical engineering study and look forward to continued participation during the design and construction phases of this project. If you have any questions pertaining to this report or if we may be of further service, please contact us at your convenience.

Respectfully submitted, Jubair Hossain, Ph.D., P.E. 9-4-25 Maisha Masiyat, E.I.T.

President ________________________ Staff Engineer

HTS, Inc. Consultants

F-3478

MM/JH:rg

H:\2025\250-299\25-S-274 SH-105 W. Gravity Sewer Upgrade - City of Conroe\Report\25-274.docx

416 Pickering Street, Houston, TX 77091 www.htshouston.com

Phone: 713-692-8373

Fax: 713-692-8502

Toll Free: 1-800-692-TEST

TABLE OF CONTENTS

Page No.

1. INTRODUCTION

2. PURPOSE AND SCOPE OF WORK

3. FIELD EXPLORATION

3.1 FIELDWORK INFORMATION AND METHODS

4. LABORATORY TESTING

4.1 LABORATORY TESTING METHODS

5. DESCRIPTION OF SUBSURFACE SOIL AND GROUNDWATER CONDITIONS .. 7

5.1 SUBSURFACE SOIL STRATA

5.2 GROUNDWATER CONDITIONS

6. ENGINEERING ANALYSIS AND RECOMMENDATIONS

6.1 ENGINEERING ANALYSIS AND METHODS

6.2 RECOMMENDED EARTH PRESSURE DESIGN PARAMETERS FOR DESIGN OF PERMANENT

BELOW GROUND STRUCTURES

6.3 COMPUTATION OF BRACING PRESSURES

6.4 RECOMMENDED DESIGN REQUIREMENTS FOR TEMPORARY SHORING AND BRACING FOR

EXCAVATIONS

6.5 EXCAVATION DEWATERING REQUIREMENTS

6.6 SANITARY SEWER DESIGN, BEDDING, AND BACKFILL REQUIREMENTS

7. CONSTRUCTION CONSIDERATIONS

8. CLOSING REMARKS

LIST OF TABLES

Table 1.1: Summary of Project Description

Table 2.1: Summary of the Soil Borings Distribution

Table 3.1 Summary of Soil Borings

Table 3.2 Summary of Field Investigation Method

Table 4.1 Summary of Laboratory Tests

Table 5.1 Summary of Surface Profile (Boring No. B-01 through B-09)

Table 5.2 Summary of Surface Profile (Boring No. B-10)

Table 6.1 Equivalent Fluid Pressures

Table 6.2 Lateral Earth Pressure Coefficients

APPENDIX

SITE VICINITY MAP ............................................................................................................. APPENDIX A

PLAN OF BORINGS .............................................................................................................. APPENDIX B

BORING LOGS ....................................................................................................................... APPENDIX C

SUBSURFACE PROFILE DIAGRAM................................................................................... APPENDIX E

OSHA STANDARDS AND INTERPRETATIONS ............................................................... APPENDIX F

1. INTRODUCTION

This report presents the primary findings, conclusions, and recommendations of the geotechnical investigation pertaining to the design and construction of the Proposed SH-105 West Gravity Sewer

Upgrade at the LaSalle to Highland Hollow in Conroe, Texas. The site vicinity map is shown in

Appendix A.

Project information was provided to HTS by Ms. Jennifer Gilmore with City of Conroe through an email dated May 23, 2025. Based on HTS’s review of the information provided, a summary of our understanding of the proposed project is provided in Table 1.1 below.

TABLE 1.1: SUMMARY OF PROJECT DESCRIPTION

Site Location LaSalle to Highland Hollow, Conroe, Texas.

Site History

Based on historical Google Earth imagery, portion of the site is developed with SH-105, remaining of the site has an existing ditch and tress.

Project Items

HTS understands that the project includes approximately

4,750 linear feet of 30-inch and 1,350 linear feet of 18-inch gravity sanitary sewer lines to upgrade the existing 12-inch, 15-inch, and 18-inch sewer lines along SH 105 West, from

LaSalle Avenue to Highland Hollow.

This geotechnical investigation was performed by HTS, Inc. Consultants (HTS) for City of Conroe in accordance with HTS Proposal No. 25-00217 dated June 2, 2025. The work authorization was provided on June 5, 2025, by Mr. Tara B. Gaha, Senior Assistant City Engineer with City of

Conroe.

2. PURPOSE AND SCOPE OF WORK

The purpose of the geotechnical investigation was to provide recommendations regarding the following items:

• Lateral earth pressures on underground structures,

• Soil classifications for use in defining OSHA trench shoring and bracing design requirements,

• Dewatering requirements for utility excavations,

• Utility bedding requirements, and

• Utility excavation and backfilling requirements.

The scope of work for this geotechnical investigation consisted of the following items:

• Drill and sample a total of 10 geotechnical borings within the area of the proposed development. The depth and number of borings are selected by the client and is provided in

Table 2.1 below. The boring locations are shown in Appendix B.

TABLE 2.1: SUMMARY OF THE SOIL BORINGS DISTRIBUTION

Boring Number Boring Depth (ft) Total Footage (ft)

B-01 9 9

B-02, B-03 12 24

B-04 and B-08 14 28

B-05 18 18

B-06 and B-10 16 32

B-07, B-09 14 28

Total - 139

• Obtain both disturbed and relatively undisturbed soil samples from the borings with continuous samples being taken from the ground surface.

• Measure the depth to groundwater in the borings during and after the completion of drilling.

• Backfill the borings with soil cuttings after the completion of drilling activities.

• Perform laboratory soil tests on samples obtained during the drilling of the borings in order to determine the engineering properties of the soil.

• Characterize the site subsoil and groundwater conditions and provide the results on the boring logs.

• Complete engineering analyses as necessary to develop recommendations pertaining to potential uplift of underground structures due to upward acting hydrostatic pressures caused by ground water conditions, lateral earth pressures on underground structures, dewatering requirements for utility excavations, utility trench shoring and bracing requirements, OSHA soil type classifications pertinent to trench shoring and bracing design, utility excavation/backfill requirements, and utility bedding requirements. Utility bedding and backfill requirements will be in accordance with the Montgomery County and City of Conroe criteria.

• Submit a pdf file of a report which presents the results of the geotechnical investigation.

The scope of services for this geotechnical study did not include an environmental assessment for determining the presence or absence of wetlands, or hazardous or toxic materials in the soil, surface water, groundwater, or air on or below, or around this site. Any statements in this report or on the boring logs regarding odors, colors, and unusual or suspicious items or conditions are strictly for informational purposes. An Environmental Site Assessment (ESA) is advisable prior to construction.

3. FIELD EXPLORATION

3.1 FIELDWORK INFORMATION AND METHODS

For this geotechnical investigation, a total of ten (10) geotechnical borings (Borings B-01 through

B-10) were drilled and sampled between August 8, 2025, and August 25, 2025, at the locations shown in Appendix B. The boring locations were selected by the client and staked in the field by

HTS representative. GPS coordinates of the boring locations were obtained. The depths, approximate ground elevations, as well as their co-ordinates, are shown in Table 3.1 below based on the handheld GPS and Google Earth elevation information.

TABLE 3.1 SUMMARY OF SOIL BORINGS

Boring

Designation

Total

Depth Of

Boring

(Feet)

Approximate

Ground Elevation

(Feet)

Approximate

Latitude

(Degree)

Approximate Longitude

(Degree)

B-01 9 +146 30°20'33.57"N 95°32'14.15"W

B-02 12 +144 30°20'33.68"N 95°32'8.43"W

B-03 12 +143 30°20'34.09"N 95°32'0.60"W

B-04 14 +141 30°20'34.24"N 95°31'53.38"W

B-05 18 +141 30°20'33.71"N 95°31'46.69"W

B-06 16 +141 30°20'32.43"N 95°31'46.60"W

B-07 13 +138 30°20'31.11"N 95°31'37.61"W

B-08 14 +133 30°20'29.17"N 95°31'30.70"W

B-09 14 +129 30°20'26.80"N 95°31'25.53"W

B-10 16 +126 30°20'19.49"N 95°31'27.48"W

The field exploration methods are described in Table 3.2 below.

TABLE 3.2 SUMMARY OF FIELD INVESTIGATION METHOD

Drilling Equipment Track-mounted drilling rig

Drilling Method Continuous flight augers

Drilling Procedure Applicable ASTM and HTS Safety Manual

Field Testing Hand Penetrometer, Standard Penetration Test

Sampling Procedure Soils: ASTM D1587/1586

Sampling Frequency Continuously to termination depth.

Frequency of Groundwater

Level Measurements

During drilling and approximately 15 minutes after groundwater was initially encountered.

Boring Backfill Procedures After the completion of the fieldwork, open boreholes were backfilled with soil cuttings.

During field activities, the encountered subsurface conditions were observed, logged, and visually classified (in general accordance with ASTM D2487). Field notes were maintained to summarize soil types and descriptions, water levels, changes in subsurface conditions, and drilling conditions.

4. LABORATORY TESTING

4.1 LABORATORY TESTING METHODS

For the current geotechnical study, a laboratory testing program was conducted to obtain engineering properties for use in performing engineering analyses and to adjust field soil classifications. The following Table 4.1 Summarized laboratory tests were performed:

TABLE 4.1 SUMMARY OF LABORATORY TESTS

Laboratory Test Test Standard

Moisture Content of Soils ASTM D 2216

Percent Soil Particles Passing No. 200 Sieve ASTM D 1140

Liquid Limit, Plastic Limit, and Plasticity Index of Soils ASTM D 4318

Unconfined Compressive Strength of Cohesive Soils ASTM D 2166

The test results are presented on the boring logs provided in Appendix C. A key to terms and symbols used on the logs is presented also in Appendix C. All tests were performed in accordance with applicable ASTM procedures and methods, and soil classifications were completed in accordance with the procedures and guidelines of ASTM D 2487 and ASTM D 2488.

Portions of samples not altered or consumed by laboratory testing will be discarded 60 days from the date shown in this report.

5. DESCRIPTION OF SUBSURFACE SOIL AND GROUNDWATER CONDITIONS

5.1 SUBSURFACE SOIL STRATA

The boring logs were prepared by using both field visual classifications and the results of laboratory testing. The stratification lines shown on the boring logs represent the approximate boundaries between soil types and the transitions between soil types may be gradual.

The results of the field and laboratory testing have been used to generalize a subsurface profile at the project site. The subsurface descriptions mentioned in the tables below provide a highlighted generalization of the major subsurface stratification features and material characteristics. A subsurface profile diagram is also presented in Appendix D.

TABLE 5.1 SUMMARY OF SURFACE PROFILE (BORING NO. B-01 THROUGH B-09)

Stratum Depth

(Feet) Soil Type

LL

Range

PI

Range

Passing

#200

Sieve

SPT N

Range

Su

Range

(tsf)

I* 0 – 18

Silty Clayey Sand (SC-SM), Clayey Sand (SC), Silty Sand

(SM)

NP to 51 NP to

16 to 49 4 to 26

0.45 to

1.2

*Sandy Fat Clay (CH) was encountered at depths from 2 feet through 4 feet in Boring Nos. B-02. Sandy Lean Clay (CL) was encountered at depths from 0 feet through 6 feet in Boring Nos. B-03, 6 feet through 10 feet in Boring Nos. B-04 and

8 feet through 18 feet in Boring Nos. B-05.

TABLE 5.2 SUMMARY OF SURFACE PROFILE (BORING NO. B-10)

Stratum Depth

(Feet) Soil Type

LL

Range (%)

PI Range

% Passing

#200 Sieve

SPT N

Range

Su

Range

(tsf)

I 0 – 14 Sandy Lean Clay (CL) 32 to 34 16 to 17 52 to 59 --

0.85 to

1.2

II 14 – 16 Silty Sand (SM) -- -- -- 10 --

Where: LL= Liquid limit (%)

PI = Plasticity Index

NP = Non Plastic

N = Standard Penetration Test blow count (blows/foot)

Su = Undrained Shear Strength based on Unconfined Compressive Strength

5.2 GROUNDWATER CONDITIONS

Groundwater was not encountered during drilling in Borings Nos. B-01 through B-09. Groundwater was encountered at a depth of 14.5-feet during drilling in Boring No. B-10. Approximately 15 minutes after groundwater was initially encountered, the water level was measured at a depth of

13.4-feet below the existing ground surface in Boring Nos. B-10.

The groundwater conditions described above are shown on the boring logs provided in Appendix C.

The depth to groundwater was obtained by:

• Observing the drilling operations and the free moisture contained in the samples recovered during drilling, and

• Obtaining water level measurements in the borings during drilling.

It is possible that seasonal variations will cause fluctuations in the water levels measured at the time of our field investigation. Additionally, perched water may be encountered in discontinuous zones within the soil layers. We recommend that the contractor determines the groundwater level at the site at the time of construction in order to determine the impact, if any, of the groundwater to the construction activities. It should be noted that recommendations contained in this report are based on groundwater depths at the time of this geotechnical investigation and that an accurate determination of the true groundwater levels may require several days or even months of observations.

6. ENGINEERING ANALYSIS AND RECOMMENDATIONS

6.1 ENGINEERING ANALYSIS AND METHODS

Engineering analyses were performed in order to develop design parameters that can be used for the proposed development. Analyses performed included:

• Analyses of subsurface soil grain size and plasticity characteristics and site groundwater levels as necessary to identify potential dewatering requirements,

• Analyses of subsurface soil grain size, plasticity, and shear strength properties as necessary to categorize the site subsurface soil and groundwater conditions with regard to OSHA requirements for trench shoring/bracing,

• Analyses to determine lateral earth pressure design parameters that can be used in the design of below ground structures and temporary shoring and bracing for excavations, and

• Backfill and bedding requirements for underground utilities.

6.2 RECOMMENDED EARTH PRESSURE DESIGN PARAMETERS FOR DESIGN OF PERMANENT

BELOW GROUND STRUCTURES

Below ground or earth retaining structures may be built as part of the project. These structures should be designed as earth retaining structures. The following recommendations are for typical earth retaining structures constructed with backfill behind the structures.

The earth’s pressure on the structures depends on the extent, degree of compaction, and the type of backfill that will be placed behind the wall or around the structure. The equivalent fluid pressure values for various back-fill material types based on in-situ soil present are shown in Table 6.1 below. Table 6.2 shows active, at rest, and passive earth pressure coefficients. Active earth pressure condition is applicable, if horizontal movement can occur along the structure height. If the structures are restrained at the top, at-rest earth pressure condition is applicable.

• The equivalent fluid pressure values shown in Table 6.1 below are applicable for horizontal backfill surfaces. Also, the values are applicable if the backfill behind the walls/structures extend to a minimum distance equal to the wall height. For sloping backfill, the lateral earth pressure values could be significantly different.

• The earth pressure values for the above water table condition correspond to the total unit weight of soil and the earth pressure values for the below water table condition correspond to the buoyant or submerged unit weight of soil.

• Any additional lateral loads due to surcharge and live loads should also be included in the design. A minimum uniform surcharge pressure of 250 psf should be included in the design for the pavement and traffic loads. The lateral pressure on the wall due to a uniform surcharge load can be taken as earth pressure coefficient values shown in the table multiplied by the surcharge pressure.

• Drainage systems should be provided to collect/remove water and to prevent hydrostatic pressure on the walls. If provisions to prevent accumulation of water behind the walls are not provided, the walls should be designed to resist the hydrostatic head in addition to the buoyant lateral earth pressures. The hydrostatic pressures should be accounted for the full height of the wall.

• Placement and compaction of backfill materials in layers alongside a vertical structure tend to produce greater at-rest pressures than uncompacted fill and natural deposits. Lateral pressures change gradually in accordance with wall movement and reach the full active or passive condition only when adequate movement occurs. For compacted backfill material, earth pressure should be considered for the design of the wall.

TABLE 6.1 EQUIVALENT FLUID PRESSURES

Equivalent Fluid Pressures

(Pounds per Square Foot per Foot of Wall Height)

Type of Properly Compacted Backfill

Behind the Retaining System

Soil Parameters

Active Condition

(Horizontal

Backfill)

At Rest Condition

(Horizontal

Backfill)

Above

W.T.

Below

W.T.

Above

W.T.

Below

W.T.

Select Fill

Wet unit weight of 125 pcf, Effective Cohesion (c') of

0 psf and Effective Friction Angle (φ') of 30°

42 83 62 94

On-site Sandy Lean Clays

Wet unit weight of 128 pcf, Effective Cohesion (c') of

0 psf and Effective Friction Angle (φ') of 22°

58 92 80 103

On-site Sandy Fat Clays

0 psf and Effective Friction Angle (φ') of 18°

66 95 86 106

On-site Clayey Sand/Silty Clayey Sand

Wet unit weight of 128 pcf, Effective Cohesion (c') of

43 84 64 95

On-site Silty Sand

45 83 62 94

Notes: (W.T.): Water Table

a) Values provided assume that the materials are compacted to at least 95 percent of the Standard Proctor maximum dry density (ASTM D 698) within 2 percentage points of the optimum moisture content.

b) If granular soils are used, a minimum of 2 feet of clay should be placed over the granular soils.

TABLE 6.2 LATERAL EARTH PRESSURE COEFFICIENTS

Type of Properly Compacted Backfill

Behind the Retaining System

Soil Parameters

Active

Condition

(Horizontal

Backfill)

At-Rest

Condition

(Horizontal

Backfill)

Passive

Condition

(Horizontal

Backfill)

Select Fill

Wet unit weight of 125 pcf, Effective Cohesion (c') of 0 psf and Effective Friction Angle (φ') of 30°

0.33 0.50 3.00

On-site Sandy Lean Clays

Wet unit weight of 128 pcf, Effective Cohesion (c') of 0 psf and Effective Friction Angle (φ') of 22°

0.45 0.63 2.20

On-site Sandy Fat Clays of 0 psf and Effective Friction Angle (φ') of 18°

0.53 0.69 1.89

On-site Clayey Sand/Silty Clayey Sand

Wet unit weight of 128 pcf, Effective Cohesion (c')

0.33 0.50 3.00

On-site Silty Sand

0.33 0.50 3.00

Note: Values provided assume that the materials are compacted to at least 95% of the Standard Proctor maximum dry density (ASTM D 698), within 2 percentage points of the optimum moisture content.

The weights of equivalent fluid for the passive case and the passive earth pressure coefficients shown above do not include a safety factor. It is recommended that for design purposes, a factor of safety of 2 be applied to the weights of equivalent fluid for the passive case and the passive earth pressure coefficients.

6.3 COMPUTATION OF BRACING PRESSURES

Lateral pressures resulting from construction equipment, traffic loads, or other surcharge loads should be taken into account by adding the equivalent uniformly distributed surcharge to the design lateral pressures. Hydrostatic pressure, if any, should also be considered. The active earth pressure at depth z can be determined by Equation (1) as provided below and using the soil parameters presented in previous section.

pa = (qs + h1 + ′h2) Ka + wh2 – 2c√Ka Equation (1) where, pa = active earth pressure, psf qs = uniform surcharge pressure, minimum 250 psf

, ' = wet unit weight and buoyant unit weight of soil h1 = depth from ground surface to groundwater table h2 = z-h1, depth from groundwater table to the point under consideration z = depth below ground surface for the point under consideration c = cohesion of clayey soils, psf

Ka = coefficient of active earth pressure w = unit weight of water, 62.4 pcf

If there is water behind the bracing, hydrostatic pressure should be included in the design.

If excavations are located close to existing structures, we recommend using the coefficient of at-rest earth pressure (K0) for design instead of the use of active earth pressure coefficient (Ka) to reduce the potential for distress to the existing structures.

6.4 RECOMMENDED DESIGN REQUIREMENTS FOR TEMPORARY SHORING AND BRACING FOR

EXCAVATIONS

The contractor is solely responsible for designing and constructing stable protection systems for excavations such as support systems, sloping and benching systems, shield systems, and other systems that provide protection.

Temporary special shoring, for use in the installation of structures or utilities that will require excavations deeper than 5 feet, should consist of vertical or sloped cuts, benches, shields, support systems, or other systems that will provide necessary protection in accordance with OSHA

Standards and Interpretations, 29 CFR 1926, Subpart P, “Excavations”.

If OSHA Standards and Interpretations, 29 CFR 1926, Subpart P, “Excavations” is used for the design of temporary excavation protection systems, the site clay layers should be categorized as

Type B soils while the clay soils below the groundwater table and sands should be categorized as

Type C soils.

The definitions of Type B and Type C soils are provided in Appendix A of the OSHA Standards and Interpretations, 29 CFR 1926, Subpart P, “Excavations5” (www.osha.gov). In order to eliminate the potential for caving of trench excavations, trench safety shall be implemented for trench excavations that are deeper than 5 feet. The diagrams of maximum allowable slopes for trench excavation and the diagram to use with a combination of bracing and open cuts for trench excavation are presented in Appendix E of this report.

6.5 EXCAVATION DEWATERING REQUIREMENTS

Groundwater was not encountered during drilling in Borings Nos. B-01 through B-09. Groundwater was encountered at a depth of 14.5-feet during drilling in Boring No. B-10. Approximately 15 minutes after groundwater was initially encountered, the water level was measured at a depth of

13.4-feet below the existing ground surface in Boring Nos. B-10. Based on the filed exploration, it is expected that groundwater may be encountered at excavations greater than 13-feet for this project.

However, depending on seasonal fluctuations and occurrence of rain within the construction stage, seepage water may occur at the excavations shallower than the depth discussed. The use of a dewatering system consisting of sump and pumps, well points, vacuum well points, and any other suitable dewatering system may be required. The dewatering system should be designed by a dewatering contractor.

http://www.osha.gov/

If the excavation is carried out below the groundwater table and a significant amount of the soils at or near the bottom of the excavation are sands or low-plasticity clays, the bottom can fail by blow-out (boiling) at the bottom when a sufficient hydraulic head exists. The potential for boiling or in-flow of granular soils increases where the groundwater level is high. If this condition is present during the construction activities, it is recommended that the groundwater level be lowered to at least 3 feet below the excavation in order to reduce the potential for boiling of excavation terminating in granular soils below groundwater. In extreme conditions, mechanical or chemical stabilization of the granular soils may be required as desired by the specialty contractor.

6.6 SANITARY SEWER DESIGN, BEDDING, AND BACKFILL REQUIREMENTS

Sanitary sewers may be designed by using conventional conduit formulas and assuming a negative projection condition for the computation of loadings.

The total load on sanitary sewers will consist of the weight of the compacted backfill above the pipe, the weight of the pavement, and live loadings where applicable. The wet unit weight of compacted backfill is estimated to be 130 pcf for clayey sand/lean clay backfill material.

Trench widths, trench foundations, bedding and backfill for the proposed sanitary sewers lines should be designed and installed as specified by Montgomery County Development Regulations dated March 2025.

Using City of Conroe Design Guidelines

Sanitary sewer trenches should be excavated with trench widths that comply with the requirements of Division VII (Sanitary Sewer Design Requirements) of the City of Conroe - Department of

Community Development, Engineering Division (COC-DOCDED) “Design Manual for Sanitary

Sewers, Water Mains, Storm Drainage, and Street Paving” City Ordinance # 1314-96 dated May 9, 1996 and March 2009 Revision. Sanitary sewer line trench widths, trench foundations, bedding, and backfill should satisfy the requirements of Drawing No. 1201, Detail Nos. S-1 through S-9, S-11, S-

16, and S-19.

7. CONSTRUCTION CONSIDERATIONS

The recommendations provided below should be followed with regard to the construction of the

Proposed SH-105 West Gravity Sewer Upgrade at LaSalle to Highland Hollow in Conroe, Texas.

• Fill material and fill compaction should comply with the recommendations provided in this report.

• Materials testing should be performed so as to assure that acceptable materials and construction methods are provided by the contractor.

• Backfill placement operations should be monitored and the backfill tested to assure compliance with the current City of Conroe Standard Specifications.

8. CLOSING REMARKS

HTS has performed a geotechnical investigation pertaining to the design and construction of the

Proposed SH-105 West Gravity Sewer Upgrade at LaSalle to Highland Hollow in Conroe, Texas.

This report has been prepared for the exclusive use of the City of Conroe and its authorized representatives in accordance with generally accepted soil and foundation engineering practices. No other warranty, expressed or implied, is made.

In the event that changes are made in the nature, design, or location of the proposed project, the conclusions, data, and recommendations contained in this report shall not be considered valid unless the changes are reviewed, and the findings and recommendations of this report are modified or verified in writing. The analyses and recommendations presented in this report are based upon data obtained from ten (10) geotechnical borings that were drilled between August 8, 2025, and August

25, 2025. The nature and extent of variations within the subsurface materials may not become evident until after construction is initiated. If significant variations in the subsurface materials are encountered during construction, it may be necessary to re-evaluate the recommendations provided in this report.

APPENDIX A

SITE VICINITY MAP

Vicinity Map Appendix A

HTS Project No.: 25-S-274

LaSalle to Highland Hollow

Proposed SH-105 West Gravity Sewer Upgrade

Project Boundary

Project Location

LEGEND

APPENDIX B

PLAN OF BORINGS

LaSalle to Highland Hollow

HTS Project No.: 25-S-274

Boring Locations Appendix B

Proposed SH-105 West Gravity Sewer Upgrade

APPENDIX C

BORING LOGS

Slickensided ------- Having planes of weakness that appear slick and glossy. The degree of slickensidedness depends upon the spacing of slickensides and the ease of breaking along these planes.

Fissures ------------- Containing shrinkage or relief cracks, often filled with fine sand or silt; usually more or less vertical.

Pocket --------------- Inclusion of material of different texture that is smaller than the diameter of the sample.

Parting --------------- Inclusion less than 1/8 inch thick extending through the sample. NO GRAB Seam ----------------- Inclusion 1/8 inch to 3 inches thick extending through the sample. SAMPLE SAMPLE Layer ----------------- Inclusion greater than 3 inches thick extending through the sample.

Laminated ---------- Soil sample composed of alternating partings or seams of different soil types.

Interlayered---------- Soil sample composed of alternating layers of different soil types.

Intermixed ---------- Soil sample composed of pockets of different soil types and layered or laminated structure is not evident. SHELBY SPT Calcareous--------- Having appreciable quantities of carbonate. TUBE

Number of blows for each 6-inch increment of split spoon penetration.

Number of blows of split spoon penetration for the indicated depth of penetration in inches.

MAJOR LETTER TYPICAL

DIVISIONS SYMBOL DESCRIPTIONS

GRAVEL & CLEAN WELL GRADED GRAVEL, GRAVEL-SAND Degree Plasticity Index GRAVELY GRAVEL MIXTURES WITH LITTLE OR NO FINES None - - - - - - 0 - 4

SOILS (LITTLE OR POORLY GRADED GRAVEL, GRAVEL-SAND Slight - - - - - - 5 - 10 LESS THAN NO FINES) MIXTURES WITH LITTLE OR NO FINES Medium - - - - - - 11 - 20

50% PASSING W/ APPRECIABLE SILTY GRAVEL, GRAVEL-SAND-SILT MIXTURES High - - - - - - 21 - 40 NO. 4 SIEVE FINES GC CLAYEY GRAVELS, GRAVEL-SAND-CLAY MIXTURES Very High - - - - - - > 40

SANDS CLEAN SANDS SW WELL GRADED SAND, GRAVELY SAND (LITTLE FINES)

MORE THAN LITTLE FINES SP POORLY GRADED SANDS, GRAVELY SAND (L.FINES)

50% PASSING SANDS WITH SM SILTY SANDS, SAND-SILT MIXTURES

NO. 4 SIEVE APPRECIABLE FINES SC CLAYEY SANDS,SAND-CLAY MIXTURES Very Soft - - - - - - INORGANIC SILTS & VERY FINE SANDS,ROCK FLOUR Soft - - - - - -

SILTS AND CLAYS SILTY OR CLAYEY FINE SANDS OR CLAYEY SILT W/ LOW PI Firm - - - - - - LIQUID LIMIT INORGANIC CLAY OF LOW TO MEDIUM PI LEAN CLAY Stiff - - - - - -

LESS THAN 50 GRAVELY CLAYS, SANDY CLAYS, SILTY CLAYS Very Stiff - - - - - - OL ORGANIC SILTS & ORGANIC SILTY CLAYS OF LOW PI Hard - - - - - -

INORGANIC SILTS, MICACEOUS OR DIATOMACEOUS Su =Undrained Shear Strength; bpf = blows/ft

SILTS AND CLAYS FINE SANDY OR SILTY SOILS, ELASTIC SILTS

LIQUID LIMIT INORGANIC CLAYS OF HIGH PLASTICITY

50 OR GREATER FAT CLAYS SPT (bpf)

OH ORGANIC CLAYS OF MED TO HIGH PI, ORGANIC SILT 0 - 4

PEAT AND 5 - 10

OTHER HIGHLY ORGANIC SOILS 11 - 30

31 - 50 > 50

3/4"

BOUL- GRAVEL SAND

-DERS

152 76.2 19.1 4.76 2.0 0.42 0.074

NOTES:

The boring logs and related information depict subsurface conditions only at the specific locations and dates indicated. Soil conditions and water levels at other locations may differ from conditions occuring at these boring locations. Also the passage of time may result in a change in the conditions at these boring locations.

REFERENCES:

(1) Soil Mechanics in Engineering Practice, Terzhagi and Peck, 1967

(2) ASTM D 422

0.001

No.40

ARTIFICIALLY DEPOSITED AND OTHER UNCLASSIFIED SOILS AND MANMADE

SOIL MIXTURES

SPLIT-SPOON SAMPLER DRIVING RECORD

Blows Per Foot

8-10-12 50/5"

6"

COARSE FINE

0.005

CLASSIFICATION OF GRANULAR SOILS (2)

UNCLASSIFIED FILL MATERIALS

COBBLES

No.200No.10No.4 3"

U.S. STANDARD SIEVE SIZE(S)

TERMS AND SYMBOLS USED ON LOGS

SAMPLER TYPE

1.00 - 2.00

COARSE MEDIUM FINE

SILT CLAY

GW

GRAIN SIZE IN MM

2.00 - 4.00

GP

GM

ML

HIGHLY ORGANIC SOIL

GROUNDWATER DATA

SOIL STRUCTURE

Water level during drilling.

UNIFIED SOIL CLASSIFICATION SYSTEM - ASTM D 2487

PT

CL

Density/Consistency

Very Loose Loose

Water Level after 24 hours.

COHESIVE SOILS (1)

A) Degree of Plasticity

0.25 - 0.50

> 4.00

< 0.25 Su, ksf

15 - 30 > 30

Dense Very Dense bpf = blows/ft

COARSE

GRAINED

SOILS

LESS

THAN 50%

PASSING

NO. 200

SIEVE

FINE

GRAINED

SOILS

LESS

THAN 50%

PASSING

NO. 200

SIEVE

0.50 - 1.00

MH

CH

GRANULAR SOILS (1)

B) Consistency SPT (bpf)

0 - 2 2 - 4 4 - 8 8 - 15

Medium Dense

NP

NP

NP

SILTY CLAYEY SAND (SC-SM), dark brown and dark gray

SILTY SAND (SM), loose, brown and gray

SC-SM

SM

APPROXIMATE SURFACE ELEVATION: 146 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 1 (Page 1 of 1)

UU

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LA

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M

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M O

IS

T

U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 9 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 9 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/8/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-01

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'33.57N

LONGITUDE: 95°32'14.15W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

SILTY SAND (SM), brown

SANDY FAT CLAY (CH), very stiff, reddish brown

CLAYEY SAND (SC), loose, brown and gray

SM

CH

SC

APPROXIMATE SURFACE ELEVATION: 144 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 2 (Page 1 of 1)

UU

P

LA

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IC

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M

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M O

IS

T

U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 12 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 12 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/8/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-02

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'33.68N

LONGITUDE: 95°32'8.43W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

SANDY LEAN CLAY (CL), hard, brown and gray

CLAYEY SAND (SC), brown and gray

CL

SC

APPROXIMATE SURFACE ELEVATION: 143 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 3 (Page 1 of 1)

UU

P

LA

S T

IC

LI

M

IT

M O

IS

T

U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 12 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 12 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/8/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-03

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'34.09N

LONGITUDE: 95°32'0.60W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

CLAYEY SAND (SC), brown and gray

SANDY LEAN CLAY (CL), very stiff, brown and gray

CLAYEY SAND (SC), medium dense, brown and gray

SC

CL

SC

APPROXIMATE SURFACE ELEVATION: 141 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 4 (Page 1 of 1)

UU

P

LA

S T

IC

LI

M

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M O

IS

T

U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 14 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 14 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/8/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-04

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'34.24N

LONGITUDE: 95°31'53.38W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

SILTY SAND (SM), brown

CLAYEY SAND (SC), loose to medium dense, gray

SANDY LEAN CLAY (CL), stiff to very stiff, brown and gray

SM

SC

CL

APPROXIMATE SURFACE ELEVATION: 141 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 5 (Page 1 of 1)

UU

P

LA

S T

IC

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M O

IS

T

U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 18 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 18 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/8/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-05

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'33.71N

LONGITUDE: 95°31'46.69W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

NP

NP

NP

CLAYEY SAND (SC), loose, gray and brown

SILTY SAND (SM), very loose to medium dense, gray

SC

SM

APPROXIMATE SURFACE ELEVATION: 141 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 6 (Page 1 of 1)

UU

P

LA

S T

IC

LI

M

IT

M O

IS

T

U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 16 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 16 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/8/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-06

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'32.43N

LONGITUDE: 95°31'46.60W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

SILTY SAND (SM), dark gray

CLAYEY SAND (SC), loose, gray

SM

SC

APPROXIMATE SURFACE ELEVATION: 138 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 7 (Page 1 of 1)

UU

P

LA

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IC

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M

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M O

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U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 13 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 13 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/8/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-07

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'31.11N

LONGITUDE: 95°31'37.61W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

NP

NP

NP

NP

SILTY SAND (SM), brown and gray

CLAYEY SAND (SC), loose, brown and gray

SILTY SAND (SM), medium dense, gray

SM

SC

SM

APPROXIMATE SURFACE ELEVATION: 133 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 8 (Page 1 of 1)

UU

P

LA

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IC

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M

IT

M O

IS

T

U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 14 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 14 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/25/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-08

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'29.17N

LONGITUDE: 95°31'30.70W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

SILTY SAND (SM), brown

SILTY CLAYEY SAND (SC-SM), loose, gray

CLAYEY SAND (SC), loose, light gray and gray

SM

SC-SM

SC

APPROXIMATE SURFACE ELEVATION: 129 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 9 (Page 1 of 1)

UU

P

LA

S T

IC

LI

M

IT

M O

IS

T

U R

E C

O N

T E

N T

P

LA

S T

IC

IT

Y

IN

D E

X

P

A S

S

IN

G N o.

S

IE

V

E

N -B

LO

W

S /F

T

LI

Q

U

ID

LI

M

IT

UC TV

DEPTH OF BORING: 14 FEET INITIAL GROUND WATER: NOT ENCOUNTERED

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 14 FEET

SOIL DESCRIPTION

NOTES: Boring elevations and coordinates are approximate values obtained from Google Earth.

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/25/25 FINAL GROUND WATER: NOT ENCOUNTERED

LL

LOG OF BORING B-09

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'26.80N

LONGITUDE: 95°31'25.53W

HTS Project No.: 25-S-274

B O

R

IN

G

LO

G _H

O U

S T

O N

H

O U

S T

O N

T E

M P

LA

T

E .G

D T

/3 /2

5:

H :\2

5\

0-

9\

5-

S -2

S

H -1

W

. G R

A V

IT

Y

S E

W E

R U

P G

R A

D E

C

IT

Y

O F

C O

N R

O E

\B O

R

IN

G L

O G

S \2

5-

L

O G

S .G

P J

SANDY LEAN CLAY (CL), stiff to very stiff, dark gray, gray and tan

SILTY SAND (SM), loose, light gray

CL

SM

APPROXIMATE SURFACE ELEVATION: 126 feet

U S

C S

S Y

M B

O L

PROPOSED SH-105 WEST GRAVITY SEWER UPGRADE

PLATE NO: 10 (Page 1 of 1)

UU

P

LA

S T

IC

LI

M

IT

M O

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T

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O N

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N T

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Y

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A S

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IN

G N o.

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DEPTH OF BORING: 16 FEET INITIAL GROUND WATER: 14.5 FEET

SHEAR STRENGTH

(tons/square foot)

COORDINATE (X) OR EASTING:

COORDINATE (Y) OR NORTHING:

TYPE OF BORING: DRY AUGER TO 16 FEET

SOIL DESCRIPTION

NOTES: Water level: 13.4', approximately 15 minutes after groundwater was initially encountered

PL PI

0.0 0.5 1.0 1.5 2.0 2.5

416 Pickering Street Houston, Texas 77091

S A

M P

LE

S

DATE DRILLED: 8/20/25 FINAL GROUND WATER: 13.4 FEET

LL

LOG OF BORING B-10

LASALLE TO HIGHLAND HOLLOW, CONROE, TEXAS

D E

P T

H

F T

S O

IL

T

Y P

E

HP

D R

Y U

N

IT

W E

IG

H

T (p cf

LATITUDE: 30°20'19.49N

LONGITUDE: 95°31'27.48W

HTS Project No.: 25-S-274

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APPENDIX D

SUBSURFACE PROFILE DIAGRAM

Plate D-1

El ev at io n (ft

Boring elevations and coordinates are approximate values obtained from Google Earth.

Plate D-2

El ev at io n (ft

Boring elevations and coordinates are approximate values obtained from Google Earth.

APPENDIX E

OSHA STANDARDS AND INTERPRETATIONS

NOTES:

(1) For Type B soils, all simple slope excavations 20 feet or less in depth shall have a maximum slope of 1H: 1V. For Type C soils, all simple slope excavations 20 feet or less in depth shall have a maximum allowable slope of 1.5 H: 1V

(2) Maximum depth for above slopes is 20 feet, For slopes greater than 20 feet, trench protection should be designed by the Contractor's professional engineer.

Project No.

LaSalle to Highland Hollow

Date: 9/3/2025

Project:

25-S-274 Conroe, Texas

Maximum Allowable Slopes for Trench Excavations Plate E-1

Reference: OSHA, Safety and Health Regulations for Construction, 1926, Subpart A

Conroe, Texas

Project No.

Plate E-2 Combination of Bracing and Open Cuts

Open Trench Excavation Date: 9/3/2025

LaSalle to Highland Hollow 25-S-274

Project: