Geotech Report Child Development Center PN 97292.pdf

SUBSURFACE EXPLORATION

AND

GEOTECHNICAL ENGINEERING REPORT

Child Development Center

FY 25, PN 97292

Fort Gordon, Georgia

By Soils Section

Geotechnical & HTRW Branch U.S. Army Engineer District, Savannah

May 2023

This report was prepared by the Savannah District of the U.S. Army Corps of Engineers. The initials or signatures and registration designation of individuals appear on these documents within the scope of their employment as required by the Engineer Regulation 1110-1-8152.

Date: 22 May 2023

Brent A. Schrader, P.E.

PA Registration No. PE088806 Expiration Date: 30 September 2023

Leland H. Schuman, P.E.

Georgia Registration No. 25134 Expiration Date: 31 December 2023

Table of Contents

Section Page

1. PURPOSE

2. QUALIFICATION OF REPORT

3. PROJECT DESCRIPTION

4. EXPLORATION PROCEDURES

a. Site Reconnaissance

b. Field Exploration

c. Soil Infiltration Testing

5. SITE AND SUBSURFACE CONDITIONS

a. Site Description

b. Area and Site Geology

c. Subsurface Soil Conditions

d. Groundwater Conditions

e. Infiltration Rates

6. CONCLUSIONS AND RECOMMENDATIONS

a. General

b. Site Preparation

c. Foundation Design

d. Seismic Design

e. Slabs-On-Grade

f. Earth Retaining Structures and Below Grade Structures

g. Pavement Design Criteria

h. Control of Water

i. Structural Fill

j. Construction Quality Control Testing

k. Presentation of Soil Boring and Laboratory Data

l. Specifications

ATTACHMENT A: Boring Location Plan

ATTACHMENT B: Soil Test Boring Logs

ATTACHMENT C: Infiltration Test Data

SUBSURFACE EXPLORATION AND

GEOTECHNICAL ENGINEERING REPORT

Child Development Center Addition

FY 25, PN 97292

1. PURPOSE

This report has been prepared for the design of the proposed construction of the Child Development Center Addition at Fort Gordon, Georgia. The purpose of this report is to provide recommendations for the geotechnical and foundation design of the facilities and the design of storm water quality systems for the project. The recommendations included in this report are based on the project information provided by Burns and McDonnell. Changes in site layout, structural system, loads, or finished floor or finished grade elevations may affect the recommendations. The Soils Section, Geotechnical and HTRW Branch of the Savannah District should be notified immediately of the change(s) and provided the necessary information regarding any change(s) so that the new information can be reviewed. The recommendations in this report may then change as appropriate for the proposed project.

2. QUALIFICATION OF REPORT

The field exploration performed for this report determined the subsurface soil and groundwater conditions and was not intended to serve as a comprehensive assessment of site environmental conditions. No effort was made to define, delineate, or designate any area of environmental concern or of contamination. Any recommendations regarding drainage and earthwork construction are made on the basis that such work can be performed in accordance with applicable laws pertaining to environmental contamination.

3. PROJECT DESCRIPTION

The proposed addition to the Child Development Center will consist of an approximately 16,000 square feet, single-story building providing space for child activities, a staff lounge, kitchen, mechanical room, communication room, electrical room, storage rooms, and bathrooms.

The building will have continuous strip footing foundations, CMU walls, framing and roof, and a concrete slab-on-grade. The addition will have a finish floor elevation of 479 ft. NAVD88. The facility will include playground areas of approximately 23,000 square feet surrounding three sides of the proposed building. Additional site improvements will include a new fire lane and patching asphalt near the new facility, sidewalks, pavement markings, signage, storm water management features, landscaping, associated utilities, and a trash enclosure.

4. EXPLORATION PROCEDURES

a. Site Reconnaissance Prior to the field exploration, a geotechnical engineer visually inspected the site and surrounding areas. The observations were used in planning the exploration, in determining areas of special interest, and in relating site conditions to known geologic conditions in the area.

Subsurface Exploration and Geotechnical Engineering Report Child Development Center, PN 97292, FY 25 Fort Gordon, Georgia

b. Field Exploration

(1) Subsurface conditions at the project site were explored by four (4) soil test borings B-1 through B-4. The explorations were performed at the approximate locations shown on the Boring Location Plan included in Attachment A. The borings were drilled to depths ranging from 10 feet to 25 feet below ground surface (bgs). Structural borings, borings B-1 through B-3, were advanced to 25 ft bgs and a pavement boring, B-4, was advanced to a depth of 10 ft bgs.

(2) Exploration locations were established in the field by an engineer using visual methods.

Since the measurements were not precise, the locations shown on the boring location plans and the locations indicated on the boring logs should be considered approximate. The ground surface elevation at each boring location was determined by interpolation from the site topography survey;

therefore, the elevations shown on the boring logs should also be considered approximate.

(3) The soil test borings were drilled by Savannah District with a track mounted Geoprobe 7822DT drill rig with an automatic hammer. The test borings were advanced through the soils by mechanical drilling procedures, using 4 ¼ -inch hollow stem continuous flight augers with a steel fingered bit as the cutting device Split-barrel sampling with standard penetration testing (SPT) was performed at intervals shown on the boring logs. All SPT borings and soil sampling were in accordance with ASTM D1586. In the SPT borings, a soil sample is obtained with a standard 1 3/8-inch inside diameter by 2-inch outside diameter split-barrel sampler. The sampler is first seated 6 inches and then driven an additional 12 inches with blows from a 140 lb. hammer falling 30 inches. The number of blows required to drive the sampler the final 12 inches is recorded and is termed the “standard penetration resistance,” or the “N-value.” Penetration resistance, when properly evaluated, is an index of the soil’s strength, density, and foundation support capability.

(4) Soil classifications shown on the boring logs were determined in the field by a geologist. Classification of the soil samples was performed in general accordance with ASTM D2488 (Visual-Manual Procedure for Description of Soils). The soil classifications include the use of the Unified Soil Classification System described in ASTM D2487 (Classification of Soils for Engineering Purposes). Since the soil descriptions and classifications are based on visual examination and manual tests, they should be considered approximate.

(5) Logs of the soil borings graphically depicting soil descriptions and standard penetration resistances are included in Attachment B.

c. Soil Infiltration Testing

(1) Soil permeability information for infiltration rate determination was obtained from two

(2) percolation tests, PT-1 and PT-2. The locations of the percolation tests are shown on the Boring Location Plan in Attachment A. The percolation tests were performed in accordance with USACE SAD DM 110-1-1 July 1983 chapter 20. The percolation rates from the field tests were used to estimate infiltration rates using the LID Manual for Michigan-Appendix E, Soil Infiltration Testing Protocol.

(2) The Michigan method uses an area reduction factor (Rf) to account for the exfiltration occurring through the sides of a percolation hole. It assumes that the percolation rate is affected

Fort Gordon, Georgia by the depth of water in the hole and that the percolating surface of the hole is in uniform soil. The Michigan method could thus be used to convert soil percolation rates to infiltration rates as follows:

infiltration rate =

Where reduction factor (R is given by: R 1

And:

d1 = initial water depth (in.)

Δd = average/final water level drop (in.)

DIA = diameter of the percolation hole (in.)

(3) Results of the soil percolation tests and the computed infiltration rates are included in

Attachment D.

5. SITE AND SUBSURFACE CONDITIONS

a. Site Description The proposed addition will be located in the unimproved area west-northwest of the existing Child Development Center (building 18407). The site is generally flat with elevations ranging from 473 ft to 478 ft NAVD88 over the site. The finish floor elevation of the proposed addition will be 479 ft NAVD88. Numerous overhead and buried utilities are located within the project site. Site vegetation consists of mostly landscaped grasses and a few mature trees.

b. Area and Site Geology

(1) Fort Gordon is located primarily in Richmond County, Georgia, and lies on the northwestern edge of the Upper Coastal Plains geomorphic province. This broad belt of relatively flat country is underlain by a wedge of Cretaceous-age and younger continental shelf sediments that thicken to the south and southeast. The Piedmont Province, a pre-Cretaceous-age complex of igneous and metamorphic rocks, is adjacent to and northwest of the site. The regional contact between the two provinces is the Fall Line, which has no topographic expression, but is identified lithologically. The Fall Line underlies Augusta, Georgia, and trends southwesterly, passing about four miles north of Fort Gordon, and continues through Macon, Georgia, towards Columbus, Georgia.

(2) Two Coastal Plain formations are exposed on Fort Gordon, the Upper Eocene-age

Barnwell group and the Upper Cretaceous to Lower Tertiary-age Oconee group. The Barnwell group, which occurs at the higher elevations, consists primarily of interbedded, coarse to fine sands and clays. The thickness of the Barnwell group is a maximum at the southern part of the reservation, thinning to almost nothing at the northern boundary. Underlying the Barnwell group, the Oconee group, which is exposed in the valleys, consists of sands and gravels with interbedded clays, including massive white kaolin beds. The Oconee group thickens considerably to the southeast of the reservation.

Fort Gordon, Georgia

c. Subsurface Soil Conditions

(1) The subsurface testing performed across the site indicate sands are the predominant soil in the top 25 feet. These sands have varying amounts of fines, and field classifications vary between silty sand (SM), clayey sand (SC), poorly graded sand (SP), poorly graded sand with silt (SP-SM), and poorly graded sand with clay (SP-SC). Generally, the standard penetration resistances or N-values indicate very loose to loose sands to depths of approximately 10 ft.

Medium dense sands were encountered at depths below 10 ft to the termination depth of 25 ft.

(2) The above subsurface description is of a generalized nature to highlight the major subsurface stratification features and material characteristics. The boring logs should be reviewed for specific information at individual boring locations. The stratifications shown on the boring logs represent the conditions only at the actual boring locations. Variations may occur and should be expected between boring locations. The stratification lines shown on the boring logs represent approximate boundaries between the subsurface materials; the actual transitions are typically more gradual.

d. Groundwater Conditions

(1) The groundwater level was measured in the borings during and after drilling. The water table was not encountered in any of the borings.

(2) A perched-water condition occurs when water seeping downward is blocked by a low permeability soil layer, such as clayey sand or clay, and saturates the more permeable soil above

it. The perched-water level can be any number of feet above the true groundwater level. Due to the prevalence of interbedded clayey sands, at the project site, perched water conditions could be encountered in the more permeable zones (cleaner sand layers) during construction.

(3) It should be noted that groundwater conditions, including perched water, vary during periods of prolonged drought and excessive rainfall as well as seasonally. Therefore, fluctuations in the elevation of the groundwater and the occurrence of perched-water conditions should be anticipated with changing climatic and rainfall conditions.

e. Infiltration Rates Percolation test locations were selected based on information provided by Burns and

McDonnell. The percolation tests were performed below the proposed storm water management structure at its anticipated depth. The percolation rates from the field tests were used to estimate infiltration rates using the previously described Michigan Method. The infiltration rates and test depths are shown in the table below. For specific information on estimated infiltration rates see Attachment D, Infiltration Rates.

Infiltration Test

Depth (feet)

Percolation Rate (inches/hour)

Infiltration Rate (inches/hour)

PT-1 2.0 167 33

PT-2 2.1 90 16.5

6. CONCLUSIONS AND RECOMMENDATIONS

a. General

(1) The following conclusions and recommendations are based on the information available on the proposed structures, observations made at the project site, interpretation of the data obtained from the field and laboratory investigations, and previous experience with soils and subsurface conditions similar to those encountered at the site.

b. Site Preparation

(1) Following necessary demolitions of the existing facilities, clearing and removal of trees, structures, pavement, etc., the construction area should be grubbed and stripped of all vegetation, topsoil, organics, and other deleterious materials. Clean topsoil can be stockpiled and reused in landscaped areas. It is recommended that the zone of stripping extend a minimum of 10 feet beyond the outer edges of structures and pavements. Any utilities in the project area should be located and rerouted, or properly abandoned, as necessary.

(2) After topsoil stripping has been completed, any loose surface sands in the building areas should be densified by repeated passes of a large (at least 7 ton) vibratory compactor. It is recommended that a minimum of five passes be utilized with each pass being perpendicular to the last. If quick conditions result from the compaction, a delay of a few hours between passes may be necessary to allow for the dissipation of pore water pressures. The subgrade should then be proof-rolled with a fully loaded tandem-axel dump truck. Any subgrade soils which are noted to be unstable during the proof-rolling, and which cannot be stabilized by moisture conditioning and additional compaction, should be removed to the limits determined by the geotechnical engineer and replaced with structural fill.

(3) Generally, very loose to loose sands were encountered to an approximate depth of 10 ft bgs. It is recommended that the contractor’s geotechnical representative thoroughly check all footing subgrades to ensure that the subgrades are capable of supporting the design loads. If foundation subgrades are too loose to support the anticipated loads, the loose sandy soils must be removed to firm bearing and replaced with additional concrete during the placement of concrete for the footing or replaced to design subgrade with No. 57 or No. 67 stone, compacted to a non-yielding condition.

c. Foundation Design

(1) It is recommended that footings for the addition consist of conventional shallow foundations designed for a maximum net allowable soil bearing pressure of 2,000 pounds per square foot.

(2) Minimum dimensions of 30 inches for all column footings and 24 inches for all load-bearing continuous footings shall be used in foundation design to reduce the possibility of bearing capacity failure. These footings shall be embedded a minimum depth of 24 inches, as measured from the finish floor or finish grade, whichever is lower, to the bottom of the footing. All non load-bearing wall footings shall have a minimum width of 18 inches and the minimum depth shall

Fort Gordon, Georgia be 18 inches, as measured from finish floor or finish grade, whichever is lower, to the bottom of the footing.

(3) Anticipated foundation settlements were estimated for the proposed barracks. These calculations were based on the anticipated maximum column loads of 40 kips and an estimated footing dimension based on the recommended allowable soil bearing pressure of 2,000 psf. Post construction total foundation settlements and differential settlement are not expected to exceed an inch and one-half inch, respectively

(4) The resistance of footings to be subjected to uplift from transient live loads should be represented by the total weight of concrete in the footing and the weight of any soil in the vertical column directly above the footing. Although groundwater is not anticipated to be of consequence during site grading, the effect of a groundwater table on the uplift resistance of footings should be considered for any foundations that are part of storm water detention structures and for any other foundations near areas where surface run-off may accumulate or where irrigation or water service lines are present. The effect of the groundwater (or buoyancy) can be taken into account by subtracting from the total weight of concrete and soil the weight of water represented by the block of concrete and soil which is located below the groundwater level and above the bottom of the footing. The level of the groundwater should be the highest anticipated during the life of the structure. The factor of safety against uplift should not be less than 1.5.

(5) Foundation excavations should be concreted as soon as practical following excavation.

Exposure to the environment could weaken the soils at the footing bearing level should the foundation excavations remain open for an extended period of time. Bottoms of foundation excavations should be inspected immediately prior to placement of reinforcing steel and concrete to verify that adequate bearing soils are present and that all debris, mud, and loose, frozen, or water-softened soils are removed. If the bearing surface soils have been softened by surface-water intrusion or by exposure, the softened soils must be removed to adequate bearing and replaced with additional concrete during the concreting or replaced to design subgrade with No. 57 or No.

67 stone, compacted to a non-yielding condition. To minimize exposure, the final excavation (4 to 6 inches) to design subgrade could be delayed until just prior to placement of reinforcing steel and concreting. Foundation excavations must be maintained in a drained, dewatered condition throughout the foundation construction process.

d. Seismic Design

The seismic site classification for the proposed project was evaluated using the criteria given in the 2016 International Building Code (IBC 2016) section 1613. Based on the project information and soil test borings, we recommend the following parameters be used in design:

Site Classification D Maximum Considered Earthquake (MCE) spectral response acceleration for short period Sms = 0.43g MCE spectral response acceleration for 1-second period Sm1 = 0.11g Design spectral response acceleration for short period SDS = 0.29g Design spectral response acceleration for 1-second SD1 = 0.17g

Fort Gordon, Georgia

The 2016 IBC requires a site soil profile determination extending to a depth of 100 feet for seismic site classification. Boring B-3 was terminated at a depth of approximately 25 feet below existing site grades. This seismic site class definition considers similar soil continues for the remainder of the 100-foot profile. Additional exploration to deeper depths could be performed to confirm the conditions below the current depth of exploration. Alternatively, a geophysical exploration could be utilized to attempt to justify a higher seismic site class.

e. Slabs-On-Grade

(1) Based upon past experience and the subsurface conditions encountered at the site, concrete floor slabs can be supported on densified in situ soils or on fill soils placed and compacted in accordance with the specification section 31 00 00, EARTHWORK. It is recommended that all concrete slabs-on-grade in enclosed habitable areas be underlain by a minimum of 4 inches of open graded, washed pea gravel or stone, often termed “capillary water barrier,” to prevent the capillary rise of the groundwater. Nos. 57, 67, 78, or 89 stone should be used. All drawings should be consistently labeled with the term “capillary water barrier,” since this is the term utilized in Section EARTHWORK of the Specifications. Where 4 inches of capillary water barrier are used, a vertical modulus of subgrade reaction (k) of 150 pci should be used for the slab-on-grade design. A moisture barrier consisting of lapped polyethylene sheeting having a minimum thickness of 10 mils should be provided beneath building floor slabs to reduce the potential for slab dampness from soil moisture. The capillary water barrier material may be omitted under slabs-on-grade in unenclosed areas; however, the slab should be provided with a vapor barrier. The modulus of subgrade reaction should be reduced to 125 pci where the capillary water barrier material has been omitted. Concrete slabs should be jointed around columns and along supported walls to minimize cracking due to possible differential movement.

(2) The design of thickened slabs on grade to support line loads (such as partitions and light wall loads) should be in accordance with UFC-3-301-01, Structural Engineering.

(3) Construction activities and exposure to the environment often cause deterioration of the prepared slab-on-grade subgrade. Therefore, the slab subgrade soil shall be inspected and evaluated immediately prior to floor slab construction. The evaluation might include a combination of visual observations, hand rod probing, and field density tests to verify that the subgrade has been properly prepared. If unstable soil is revealed, the affected soil should be removed to firm bearing and replaced to design subgrade with suitable structural fill soil placed and compacted as recommended or replaced with additional capillary water barrier material.

f. Earth Retaining Structures and Below Grade Structures

(1) For the design and construction of any earth retaining walls with no sloping backfill and any other below grade or earth retaining structures, the following earth pressure coefficients and soil parameters should be used:

Coefficient of at-rest earth pressure (Ko) = 0.5 Coefficient of active earth pressure (Ka) = 0.33 Coefficient of passive earth pressure (Kp) = 3.00 Coefficient of friction (soil -vs- concrete, μf) = 0.35 Internal friction angle for soil backfill (φ) = 30º

Fort Gordon, Georgia

Unit weight of soil (moist) = 120 lbs/ft3 Unit weight of soil (saturated) = 125 lbs/ft3 Unit weight of soil (buoyant) = 63 lbs/ft3

(2) Drainage features such as weep holes, longitudinal drains, prefabricated geocomposite drains, and porous backfill should be utilized. Compaction of backfill within 10.0 feet of walls should be performed with hand operated equipment, such as walk behind compactors (“whacker packers” or vibratory plate compactor). If sloping backfill or toe conditions exist, the Soils Section, Geotechnical, and HTRW Branch of the Savannah District should be consulted for additional recommendations.

(3) To adequately reduce potential for time-dependent movement (creep deformation), fine grained soils such as ML, CL, MH, and CH will not be allowed for use with MSE walls and/or slopes. Well compacted, select granular fill shall be used in the reinforced zone of any MSE walls and/or slopes. Backfill to be placed against reinforced concrete retaining/foundation walls should consist of free draining granular materials. Fine grained soils such as ML, CL, MH, and CH should not be used. Where free draining granular backfill is not used, the installation of additional drainage measures to provide an adequate factor of safety against the buildup of hydrostatic pressures shall be incorporated into the design. Drains shall be adequately protected by a filter medium so that seepage water is admitted freely but movement of the soil backfill into the drain will not occur.

(4) Should mechanically stabilized earth (MSE) walls be proposed at the subject site. The walls shall be designed using the American Association of State Highway and Transportation Officials (AASHTO) design methodology as published in the Federal Highway Administration (FHWA) publication “Mechanically Stabilized Earth Walls and Reinforced Soil Slope Design and Construction Guidelines (FHWA NHI-00-043, March 2001)”. Wall designs using National Concrete Masonry Association (NCMA) design methodology will not be acceptable.

g. Pavement Design Criteria

(1) The soil types expected to be encountered under the pavements are silty sands or clayey sands. Unsatisfactory subgrade soils should be removed and replaced with satisfactory soils in accordance with the requirements of Specification Section 31 00 00 EARTHWORK. Loose surface soils were encountered at multiple boring locations across the site. After clearing and grubbing, the exposed subgrade of any areas to receive paving shall be densified with several passes of a vibratory roller.

(2) The following subgrade values for satisfactory soils are recommended for design of the pavements:

Flexible Pavement:

Compacted subgrade, use CBR of 8.

Rigid Pavement:

a) Use a corrected modulus of subgrade reaction, K of 150 psi per inch with at least four inches of compacted aggregate base course.

Fort Gordon, Georgia

b) The concrete should have a minimum design 28-day compressive strength of at least 4,000 psi utilizing a mix design that has been proven to produce concrete with a flexural strength of at least 650 psi.

h. Control of Water Water should not be allowed to collect near the foundation or on floor slab areas of the building either during or after construction. Undercut or excavated areas should be sloped toward one corner to facilitate removal of any collected rainwater, groundwater, or surface runoff. Positive site drainage should be provided to reduce infiltration of surface water around the perimeter of the building and beneath floor slabs. The following note should be added to an appropriate civil/site plate and also to an appropriate structural foundation plate of the contract drawings:

“Drainage and Dewatering: All excavations shall be performed so that the site and the area immediately surrounding the site which affects construction operations will be continually and effectively drained. The Contractor shall provide drainage and dewatering as required to ensure that all footing excavations are accomplished with the subgrade soils remaining dry and firm until after footings are placed and backfilled.

Removal of surface water, groundwater, and any perched-water conditions, which might be encountered during excavations shall be accomplished by approved means. Refer to Specification 31 00 00 EARTHWORK for additional requirements.”

i. Structural Fill In order to achieve high density structural fill, the following evaluations and recommendations are offered:

(1) Based on the soil test borings, excavated on-site soils (excluding any organics/topsoil and debris) can be used as structural fill. Some moisture content adjustment will probably be necessary to achieve proper compaction. If water must be added, it should be uniformly applied and thoroughly mixed into the soil by discing.

(2) It is recommended that the contractor have appropriate disc harrows on site during earthwork for mixing, drying, and wetting of the soils.

(3) Materials selected for use as structural fill should be free from roots and other organic matter, trash, debris, and frozen soil, and stones larger than 3 inches in any dimension, and in general, should have a liquid limit less than 50 percent and a plasticity index of less than 30. The following soils represented by their Unified Soil Classification System (ASTM D2487) group symbols will be suitable for use as structural fill: GP, GW, GM, GC, SP, SP-SM, SP-SC, SW, SC, SM, SM-SC, CL, and ML. The following soil types are considered unsuitable: Pt, OH, OL, CH, and MH.

(4) Suitable fill soils should be placed in lifts of maximum 8 inches loose measurement.

The soil should be compacted by mechanical means such as steel drum, sheepsfoot, tamping, or rubber-tired rollers. Compaction of clays is best accomplished with a sheepsfoot or tamping roller.

Periodically rolling with heavily loaded, rubber-tired equipment may be desirable to seal the

Fort Gordon, Georgia surface of the compacted fill, thus reducing the potential for absorption of surface water following a rain. This sealing operation is particularly important at the end of the work day and at the end of the week. Within confined areas or foundation excavations, we recommend the use of manually operated, internal combustion activated compactors (“whacker packers” or vibratory plate compactors). The compactors should have sufficient weight and striking power to produce the same degree of compaction that is obtained on the other portions of the fill by the rolling equipment as specified. Where hand operated equipment is used, the soils should be placed in lifts of maximum 4 inches loose measurement.

(5) It is recommended that all material to be utilized for structural fill and subgrades be compacted to minimum dry densities corresponding to 92% of the maximum dry density, and at moisture contents within +/- 2% of optimum moisture content as obtained by ASTM D1557 (Modified Proctor). The top two feet of all areas to receive pavement or structures should be compacted to 95% of its modified proctor value. The base course beneath paved areas should be compacted to 100% of the ASTM D1557 maximum dry density.

j. Construction Quality Control Testing

(1) Prior to initiating any structural fill placement and/or compaction operations, representative samples of the soils which will be used as structural fill or subgrade, both suitable on-site soils and off-site soils (borrow), should be obtained and tested to determine their classification and compaction characteristics. The samples should be carefully selected to represent the full range of soil types to be used. The moisture content, maximum dry density, optimum moisture content, grain-size, and plasticity characteristics should be determined. These tests are required to determine if the fill and subgrade soils are acceptable and for compaction quality control of the subgrades and structural fill. Tests for the above soil properties should be in accordance with the following:

Moisture Content ASTM D2216 Maximum Dry Density and Optimum Moisture ASTM D1557 Grain-Size (Wash No. 200, less hydrometer) ASTM D6913 and D1140 Plasticity ASTM D4318

(2) A representative number of in-place field density tests should be performed in the subgrade of compacted on-site soils and in the structural fill and backfill to confirm that the required degree of compaction has been obtained. In-place density tests should be performed in accordance with the sand cone method prescribed in ASTM D1556. The use of the ASTM D6938

- Standard Test Method for In-Place Density and Water Content of Soil and Soil-Aggregate by Nuclear Methods is authorized provided the test results are checked for accuracy at a minimum rate of one ASTM D1556 test for every ten ASTM D6938 tests in the same material. It is recommended that at least one density test be performed for each 2,500 square feet or portion thereof, but not less than one test per proposed structure, in compacted native soil subgrade and in each lift of compacted structural fill. It is also recommended that at least one density test be performed for each 75 linear feet in the bearing level soils of continuous footings. Density tests should be performed at 100-foot intervals along roadway subgrades. In addition, a density test should be performed for each 100 linear feet of backfill placed per foot of depth in trenches for utilities systems. Where other areas are compacted separately by manually operated compactors, Fort Gordon, Georgia a minimum of one density test should be performed for every 250 square feet, or portion thereof, of fill placed per foot of depth.

(3) Compaction control of soils requires the comparison of fill water content and dry density values obtained in the field density tests with optimum water content and maximum dry density. The performance of a laboratory compaction test on material from each field density test would provide the most accurate relation of the in-place material to optimum water content and maximum density, but it is not feasible to do this as the testing could not keep pace with fill construction. It is recommended that compaction control of the earthwork construction be performed using a “family” of compaction curves and the one-point or two-point compaction methods.

(4) Any area that does not meet the required compaction criteria should be reworked and retested. If the moisture content of the soil is within the recommended range, additional compaction may be all that is necessary to increase the density. If the moisture content is not within the recommended range, then, the moisture content should be adjusted to within the range and the area recompacted.

(5) All laboratory and field density testing should be performed by a commercial testing laboratory that has been validated by the Engineer Research and Development Center Materials Testing Center (MTC) under the Corps of Engineers laboratory inspection and validation program.

k. Presentation of Soil Boring and Laboratory Data The exploration locations at the project site are shown on the boring location plan in

Attachment A. Soil test boring logs are shown in Attachment B. These items are to be referenced and shown on the sheets of the contract drawings.

l. Specifications The Unified Facilities Guide Specifications EARTHWORK specification 31 00 00 and

CHEMICAL TERMITE CONTROL Specification 31 31 16.13 shall be included with the contract specifications.

ATTACHMENT A

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/4 /2

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LR

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L.

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H U

M

AN

L.

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B.

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H R

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S.

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US Army Corps of Engineers

U .S

. A R

M Y

C O

R

PS

O F

EN

G

IN

EE

R S

B-101

BO

R

IN

G

L O

C

AT

IO

N

P

LA

N

NOTES:

1. B-XX = SOIL BORING LOCATION

2. HORIZONTAL DATUM: NORTH AMERICAN

OF 1983 STATE PLANE COORDINATES

GEORGIA STATE PLANE EASTERN FOOT

3. AERIAL PHOTOGRAPHS MADE 2023

LEGEND

BORING LOCATION

PERC TEST LOCATION

ATTACHMENT B

Soil Test Boring Logs

Water Level Data Reading Depth Notes

477.3

465.7

455.8

452.5

After drilling Not Encountered

21.2 ft- Hole collapsed

0.2

11.8

21.8

25.0

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

Topsoil (approx. 2 inches).

POORLY GRADED SAND (SP), brown to light brown, moist, loose, mostly fine to medium sand, trace silt.

CLAYEY SAND (SC), light brown, moist, medium dense, mostly fine to coarse sand, little clay.

POORLY GRADED SAND WITH SILT (SP-SM),

brownish red, moist, dense, mostly fine to medium sand, few silt, trace clay.

BORING TERMINATED AT 25.0 ft

Notes:

1. Soils visually classified in accordance with ASTM D2488.

2. N-Value: Total blows over last 1.0 foot of 1.5-foot driven interval, unless otherwise indicated, using a 1 3/8-inch ID splitspoon with 140-pound hammer falling 30 inches.

3. The CME-750x drilling rig utilizes an automatic trip hammer. The hammer efficiency correction is 1.6.

4. Component percentages: Mostly - 50-100%;

Some- 30-45%; Little - 15-25%; Few - 5-10%; Trace - <5%.

5. No long term water readings obtained due to borehole collapse.

Fort Gordon

DISTURBED

6. THICKNESS OF OVERBURDEN

7. DEPTH DRILLED INTO ROCK

8. TOTAL DEPTH OF BORING

STARTEDVERTICAL

1. PROJECT

UNDISTURBED

NAVD88

2. HOLE NUMBER

18. SIGNATURE AND TITLE OF INSPECTOR

Geoprobe

BEARING

Kyle Killabrew

17. TOTAL CORE RECOVERY FOR BORING

2/15/23

SHEETSDRILLING LOG

12. TOTAL SAMPLES

13. TOTAL NUMBER CORE BOXES

B-1

DIVISION

11. MANUFACTURER'S DESIGNATION OF DRILL

South Atlantic Division

See Remarks

2/15/23

N/A

14. ELEVATION GROUND WATER

SHEET

3. DRILLING AGENCY

OF

COMPLETED

15. DATE BORING

DEG FROM

VERTICAL

HORIZONTAL

4-1/4" Hollow Stem Auger

INSTALLATION

8 0

INCLINED

U.S. Army Corps of Engineers - Savannah District

4. NAME OF DRILLER

5. DIRECTION OF BORING

9. COORDINATE SYSTEM

10. SIZE AND TYPE OF BIT

NAD83Child Development Center

N 1243972.729 E 657260.397

LOCATION COORDINATES

16. ELEVATION TOP OF BORING

VERTICAL

Jose Santiago, Geologist

477.5'

State Plane - Georgia East

>25' 0'

25'

Boring Designation B-1

Boring Designation B-1 SHEET 1 of 1

R Q

D

REC

FEB 08

ELEV

LE

G

EN

D

SAS FORM 1836-A

REMARKSDEPTH

N -V al ue

Bl ow s/ 0.

ft

Sa m p N o.

FIELD CLASSIFICATION OF MATERIALS

(Description)

Water Level Data Reading Depth Notes

477.8

466.2

464.0

453.0

After drilling Not Encountered

20 ft- Hole collapsed

0.3

11.8

14.0

25.0

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

Topsoil (approx. 3 inches).

POORLY GRADED SAND (SP), brown, moist, loose, mostly fine to medium sand, trace silt, trace organics.

Light brown.

POORLY GRADED SAND WITH SILT (SP-SM),

reddish brown, moist, medium dense, mostly fine to medium sand, few silt, trace clay.

CLAYEY SAND (SC), brownish red, moist, medium dense, mostly fine to medium sand, little clay.

BORING TERMINATED AT 25.0 ft

Notes:

1. Soils visually classified in accordance with ASTM D2488.

2. N-Value: Total blows over last 1.0 foot of 1.5-foot driven interval, unless otherwise indicated, using a 1 3/8-inch ID splitspoon with 140-pound hammer falling 30 inches.

3. The CME-750x drilling rig utilizes an automatic trip hammer. The hammer efficiency correction is 1.6.

4. Component percentages: Mostly - 50-100%;

Some- 30-45%; Little - 15-25%; Few - 5-10%; Trace - <5%.

5. No long term water readings obtained due to borehole collapse.

Fort Gordon

DISTURBED

6. THICKNESS OF OVERBURDEN

7. DEPTH DRILLED INTO ROCK

8. TOTAL DEPTH OF BORING

STARTEDVERTICAL

1. PROJECT

UNDISTURBED

NAVD88

2. HOLE NUMBER

18. SIGNATURE AND TITLE OF INSPECTOR

Geoprobe

BEARING

Kyle Killabrew

17. TOTAL CORE RECOVERY FOR BORING

2/15/23

SHEETSDRILLING LOG

12. TOTAL SAMPLES

13. TOTAL NUMBER CORE BOXES

B-2

DIVISION

11. MANUFACTURER'S DESIGNATION OF DRILL

South Atlantic Division

See Remarks

2/15/23

N/A

14. ELEVATION GROUND WATER

SHEET

3. DRILLING AGENCY

OF

COMPLETED

15. DATE BORING

DEG FROM

VERTICAL

HORIZONTAL

4-1/4" Hollow Stem Auger

INSTALLATION

8 0

INCLINED

U.S. Army Corps of Engineers - Savannah District

4. NAME OF DRILLER

5. DIRECTION OF BORING

9. COORDINATE SYSTEM

10. SIZE AND TYPE OF BIT

NAD83Child Development Center

N 1243873.033 E 657207.31

LOCATION COORDINATES

16. ELEVATION TOP OF BORING

VERTICAL

Jose Santiago, Geologist

478'

State Plane - Georgia East

>25'

0'

25'

Boring Designation B-2

Boring Designation B-2 SHEET 1 of 1

R Q

D

REC

FEB 08

ELEV

LE

G

E N

D

SAS FORM 1836-A

REMARKSDEPTH

N -V al ue

B lo w s/

0.

ft

S am p N o.

Water Level Data Reading Depth Notes

477.3 476.9

463.6

460.7

452.5

After drilling Not Encountered

3.5- 5.0 ft blow counts: WOH, 1,1

6.5- 8.0 ft blow counts: WOH, 1,1

22.75 ft- Hole collapsed

0.3 0.6

13.9

16.8

25.0

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

Topsoil (approx. 3 inches).

SILTY SAND (SM), dark brown, moist, loose, mostly fine to medium sand, little clay.

POORLY GRADED SAND (SP), brown to light brown, moist, very loose to loose, mostly fine to medium sand, trace silt.

POORLY GRADED SAND WITH CLAY (SP-SC),

dark brown, moist, medium dense, mostly fine to medium sand, few clay, trace silt.

CLAYEY SAND (SC), moist, medium dense, mostly fine to medium sand, little clay, trace silt.

Trace fine gravel.

BORING TERMINATED AT 25.0 ft Notes:

1. Soils visually classified in accordance with ASTM D2488.

2. N-Value: Total blows over last 1.0 foot of 1.5-foot driven interval, unless otherwise indicated, using a 1 3/8-inch ID splitspoon with 140-pound hammer falling 30 inches.

3. The CME-750x drilling rig utilizes an automatic trip hammer. The hammer efficiency correction is 1.6.

4. Component percentages: Mostly - 50-100%;Some - 30-45%;

Little - 15-25%; Few - 5-10%; Trace- <5%.

5. Weight of Hammer (WOH) - A weight of hammer event occurs during standard penetration testing when the hammer and drill string (drilling rod and split spoon sampler) are allowed to rest on the bottom of the borehole and they sink under their own weight.

6. No long term water readings obtained due to borehole collapse.

borehole collapse.

Fort Gordon

DISTURBED

6. THICKNESS OF OVERBURDEN

7. DEPTH DRILLED INTO ROCK

8. TOTAL DEPTH OF BORING

STARTEDVERTICAL

1. PROJECT

UNDISTURBED

NAVD88

2. HOLE NUMBER

18. SIGNATURE AND TITLE OF INSPECTOR

Geoprobe

BEARING

Kyle Killabrew

17. TOTAL CORE RECOVERY FOR BORING

2/16/23

SHEETSDRILLING LOG

12. TOTAL SAMPLES

13. TOTAL NUMBER CORE BOXES

B-3

DIVISION

11. MANUFACTURER'S DESIGNATION OF DRILL

South Atlantic Division

See Remarks

2/16/23

N/A

14. ELEVATION GROUND WATER

SHEET

3. DRILLING AGENCY

OF

COMPLETED

15. DATE BORING

DEG FROM

VERTICAL

HORIZONTAL

4-1/4" Hollow Stem Auger

INSTALLATION

8 0

INCLINED

U.S. Army Corps of Engineers - Savannah District

4. NAME OF DRILLER

5. DIRECTION OF BORING

9. COORDINATE SYSTEM

10. SIZE AND TYPE OF BIT

NAD83Child Development Center

N 1243770.062 E 657149.64

LOCATION COORDINATES

16. ELEVATION TOP OF BORING

VERTICAL

Jack Kaluga, Geologist

477.5'

State Plane - Georgia East

>25'

0'

25'

Boring Designation B-3

Boring Designation B-3 SHEET 1 of 1

R Q

D

REC

FEB 08

ELEV

LE

G

E N

D

SAS FORM 1836-A

REMARKSDEPTH

N -V al ue

B lo w s/

0.

ft

S am p N o.

466.0

6.5- 8.0 ft blow counts: WOH, 1,1

7.1 ft - Hole collapsed

10.0

S-1

S-2

S-3

S-4

S-5

POORLY GRADED SAND (SP), brown to light brown, moist, very loose, mostly fine to medium sand, trace silt, trace organics to 6 inches.

BORING TERMINATED AT 10.0 ft

Notes:

1. Soils visually classified in accordance with ASTM D2488.

2. N-Value: Total blows over last 1.0 foot of 1.5-foot driven interval, unless otherwise indicated, using a 1 3/8-inch ID splitspoon with 140-pound hammer falling 30 inches.

3. The CME-750x drilling rig utilizes an automatic trip hammer. The hammer efficiency correction is 1.6.

4. Component percentages: Mostly - 50-100%;Some- 30-45%; Little - 15-25%; Few - 5-10%; Trace- <5%.

5. Weight of Hammer (WOH) - A weight of hammer event occurs during standard penetration testing when the hammer and drill string (drilling rod and split spoon sampler) are allowed to rest on the bottom of the borehole and they sink under their own weight.

6. No long term water readings obtained due to borehole collapse.

Fort Gordon

DISTURBED

6. THICKNESS OF OVERBURDEN

7. DEPTH DRILLED INTO ROCK

8. TOTAL DEPTH OF BORING

STARTEDVERTICAL

1. PROJECT

UNDISTURBED

NAVD88

2. HOLE NUMBER

18. SIGNATURE AND TITLE OF INSPECTOR

Geoprobe

BEARING

Kyle Killabrew

17. TOTAL CORE RECOVERY FOR BORING

2/16/23

SHEETSDRILLING LOG

12. TOTAL SAMPLES

13. TOTAL NUMBER CORE BOXES

B-4

DIVISION

11. MANUFACTURER'S DESIGNATION OF DRILL

South Atlantic Division

See Remarks

2/16/23

N/A

14. ELEVATION GROUND WATER

SHEET

3. DRILLING AGENCY

OF

COMPLETED

15. DATE BORING

DEG FROM

VERTICAL

HORIZONTAL

4-1/4" Hollow Stem Auger

INSTALLATION

5 0

INCLINED

U.S. Army Corps of Engineers - Savannah District

4. NAME OF DRILLER

5. DIRECTION OF BORING

9. COORDINATE SYSTEM

10. SIZE AND TYPE OF BIT

NAD83Child Development Center

N 1243626.709 E 657225.32

LOCATION COORDINATES

16. ELEVATION TOP OF BORING

VERTICAL

Jack Kaluga, Geologist

476'

State Plane - Georgia East

>10'

0'

10'

Boring Designation B-4

Boring Designation B-4 SHEET 1 of 1

R Q

D

REC

FEB 08

ELEV

LE

G

E N

D

SAS FORM 1836-A

REMARKSDEPTH

N -V al ue

B lo w s/

0.

ft

S am p N o.

ATTACHMENT C

Soil Infiltration Test Data

Child Development Center Addition P.N. 97510 Ft. Gordon, Ga Engineer: BAS Date: 2/8/2023

Soil percolation tests were performed in accordance with DM 110-1-1, Jul 83, chapter 20.

Weather Conditions: Partly Sunny 40's to 50's F Various lengths of slotted pvc pipe screens were placed in each hole to minimize difficulties associated with hole cave-in.

Water levels were measured by a water level indicator with a reference point on the slotted pipe screen.

A minimum 6" water column above gravel was used as the initial height of water, subsequently recharged to this level after each reading as necessary. All times were noted by a watch with a second hand.

The Michigan method is used to estimate infiltration rates from percolation rates.

Percolation Test PT-1

Test Depth: 2 ft Reference point depth 4.73 ft

0.5'-2.0'- light brown to brown medium to fine sand, few to trace silt (SP/ SP-SM)

Time of Reading Elapsed initial reading final reading time (min.) from top of riser, ft from top of riser, ft ft/hr in/hr Rf Inf rate (in/hr)

936 9 4.00 4.73 4.87 58.40 3.19 938 2 3.98 4.39 12.30 147.60 4.27 940 2 4.39 4.73 10.20 122.40 2.02 942 2 3.60 4.13 15.90 190.80 6.19 944 2 4.13 4.60 14.10 169.20 3.19 946 2 3.93 4.33 12.00 144.00 4.60 948 2 4.33 4.70 11.10 133.20 2.29 950 2 3.70 4.21 15.30 183.60 5.65 952 2 4.21 4.60 11.70 140.40 2.95 954 2 3.60 4.18 17.40 208.80 6.04 956 2 4.18 4.58 12.00 144.00 3.10 958 2 3.67 4.24 17.10 205.20 5.65

1000 2 4.24 4.62 11.40 136.80 2.80 1004 4 3.61 4.53 13.80 165.60 4.96 1008 4 3.60 4.52 13.80 165.60 5.02 1012 4 3.54 4.50 14.40 172.80 5.26 1016 4 3.58 4.47 13.35 160.20 5.23 1020 4 3.63 4.57 14.10 169.20 4.78 1024 4 3.68 4.54 12.90 154.80 4.72 1028 4 3.57 4.50 13.95 167.40 5.17 1032 4 3.63 4.55 13.80 165.60 4.84 1036 4 3.6 4.53 13.95 167.40 4.99 33.55

Percolation Test PT-2

Test Depth: 2.1 ft Reference point depth: 4.93 ft

1'-2'- light brown medium to fine sand, few silt (SP-SM)

Time of reading Elapsed initial reading final reading time (min.) from top of riser, ft from top of riser, ft ft/hr in/hr Rf Inf rate (in/hr)

1009 3.5 4.15 4.93 13.37 160.46 3.34 1014 4.5 3.89 4.91 13.60 163.20 4.18 1018 4 4 4.86 12.90 154.80 4.00 1022 4 4 4.7 10.50 126.00 4.48 1026 4 3.98 4.53 8.25 99.00 5.05 1030 4 3.95 4.65 10.50 126.00 4.78 1034 4 4.02 4.67 9.75 117.00 4.51 1038 4 4.01 4.63 9.30 111.60 4.66 1042 4 3.96 4.58 9.30 111.60 4.96 1046 4 3.86 4.4 8.10 97.20 5.80 1050 4 3.92 4.50 8.70 104.40 5.32 1054 4 3.86 4.34 7.20 86.40 5.98 1058 4 3.77 4.21 6.60 79.20 6.64 1102 4 3.97 4.56 8.85 106.20 4.99 1106 4 3.89 4.53 9.60 115.20 5.32 1110 4 3.94 4.44 7.50 90.00 5.44 16.54

Soil Description:

0'-0.5'- Topsoil

Infiltration rate percolation rate Infiltration rate percolation rate

0'-1'- dark brown silty medium to fine sand few fine gravel (SM)

Soil Description:

Test Depth

Reference Point

Ground Surface

Backfill to hold screen in place

Well Screen

4"

Test Setup

Gravel