GEO_REPORT.pdf

REPORT OF GEOTECHNICAL EXPLORATION

DOBBINS ARB - SMALL ARMS FIRING RANGE

MARIETTA, GEORGIA

FOR

TOLAND-MIZELL ARCHITECTS

SEPTEMBER 16, 2015

ECS PROJECT NO. 10:8625

REPORT OF GEOTECHNICAL EXPLORATION

DOBBINS ARB – SMALL ARMS FIRING RANGE

MARIETTA, GEORGIA

TABLE OF CONTENTS

PAGE

INTRODUCTION 1

General 1 Project Information 1 Purposes of Exploration 2

FIELD EXPLORATION AND LABORATORY TESTING 2

Subsurface Exploration 2 Laboratory Testing Program 3

SUBSURFACE CONDITIONS 3

Regional Geology 3 Soil Conditions 4 Groundwater Conditions 5

ANALYSIS AND RECOMMENDATIONS 6

Design Implications of Undocumented Fill 6 Foundation Design and Settlement 6 Foundation Lateral Thrust - Helical Piles/Anchors 8 Ground Floor Slab Design 9 Soil Parameters 10 Slopes 10

CONSTRUCTION RECOMMENDATIONS 10

Subgrade Preparation 10 Fill Placement 11 Additional Considerations 12

CLOSING 13

APPENDIX

I. Figure 1 - Site Location Diagram

Figure 2 - Boring Location Plan

II. Unified Soil Classification System

Reference Notes for Boring Logs

Boring Logs (4)

Laboratory Testing Summary

III. ASFE Information about Geotechnical Reports

INTRODUCTION

General

This report presents the results of a geotechnical exploration for the Dobbins ARB - Small Arms

Firing Range in Marietta, Georgia. Work was performed in general accordance with ECS

Proposal No. 10: 11420 as authorized by Mr. Alan Toland with Toland-Mizell Architects on

August 13, 2015.

Project Information

This section is based on information provided and our site reconnaissance. The project site is at the existing Small Arms Firing Range at the southeast end of Dobbins Air Reserve Base in

Marietta, Georgia. A Site Location Diagram is included in the Appendix as Figure 1.

We understand that portions of the existing Small Arms Firing Range structure, including the roof/ deflection barriers, will be removed. A new pre-engineered metal building will be constructed to span over the remaining portions of the Firing Range, including the concrete wall. The new building will hold up hardened ½” steel plates in a shingle style pattern which are designed reflect live rounds to the rear of the structure.

From information provided, we understand the maximum column loads will not exceed 100 kips.

Due to the long span of the metal building frames, the lateral loads on the main frame columns foundations will be approximately 140 kips. Preliminary foundation designs to resist the lateral loads at the columns indicate that the required footing size would be approximately 22’x22’x3’.

Due to the relatively large footings, helical piles are anticipated to resist the lateral loads and reduce the foundation dimensions.

From the grading plan provided, we understand the existing finished floor elevation (FFE) ranges between 970 and 971 feet. The ground surface elevations surrounding the firing range is about 970 feet. The area to the south of the firing range slope upward to an existing parking lot. Grades along the southern slope range from 970 feet at the base of the slope up to about

985 feet near the parking lot. The rear of the existing structure is located about 20 feet from the crest of a downward slope to the north. The crest of the north slope is at 969 feet, but the grades along the northern slope were not available. No significant cut or fill is expected at this site during construction of the metal building.

The attached Boring Location Plan (Figure 2) presents the site development concept at the time of this report. If any of the information presented is incorrect or has changed, please advise

ECS so that we may reevaluate our recommendations in the light of changes in the present project concept.

Dobbins ARB - Small Arms Firing Range ECS Project No. 10:8625

Purposes of Exploration

The purposes of this exploration were to explore the soil and groundwater conditions at the site and to develop engineering recommendations to guide design and construction of the proposed project.

We accomplished the purposes of the study by:

1. Reviewing the available publications concerning local geology of the site and performing a general site reconnaissance.

2. Drilling borings to explore the subsurface soil and groundwater conditions.

3. Performing laboratory tests on selected representative soil samples from the borings to evaluate pertinent engineering properties.

4. Evaluating the field and laboratory data to develop appropriate engineering recommendations.

FIELD EXPLORATION AND LABORATORY TESTING

Subsurface Exploration

To explore the subsurface conditions at this site, a total of 4 soil test borings (B-1 to B-4) were performed near the corners of the existing firing range structure to depths of 30 feet below existing grade.

Boring locations were determined in the field by our representative who measured distances and estimated right angles from existing site features. As these methods are not precise, the boring locations shown on the attached Boring Location Plan (Figure 2) should be considered approximate.

The soil test borings were performed with an ATV mounted drill rig, which utilized hollow stem augers to advance the boreholes. No water or drilling fluid was introduced during the process.

Representative soil samples were obtained by means of the split-barrel sampling procedure in general accordance with ASTM Specification D-1586 with an automatic drive hammer. In this procedure, a 2-inch O.D., split-barrel sampler is driven into the soil a distance of 18 inches by a

140-pound hammer falling 30 inches. The number of blows required to drive the sampler through a 12-inch interval is termed the Standard Penetration Test (SPT) N-value and is indicated for each sample on the boring logs. This value can be used as a qualitative indication of the in-place relative density of cohesionless soils. In a less reliable way, it also indicates the consistency of cohesive soils.

The drill crew and an ECS representative prepared a field log of the soils encountered in the borings. After recovery, each sample was removed from the sampler and visually classified by the field crew and ECS’s representative. Representative portions of each sample were then sealed and brought to our laboratory in Marietta, Georgia for further visual examination and laboratory testing by ECS.

Laboratory Testing Program

Representative soil samples were selected and tested in our laboratory to check visual classifications and to determine pertinent engineering properties. The laboratory testing program included visual classifications of soil samples as well as gradation analysis and natural moisture content testing on selected soil samples.

A geotechnical engineer/geologist classified each soil sample on the basis of texture and plasticity in accordance with the Unified Soil Classification System. The group symbols for each soil type are indicated in parentheses followed by the soil descriptions on the boring logs.

The geotechnical engineer/geologist grouped the various soil types into the major zones noted on the boring logs. The stratification lines designating the interfaces between earth materials on the boring logs and profiles are approximate; in-situ, the transitions may be gradual.

The soil samples will be retained in our laboratory for a period of 60 days, after which, they will be discarded unless other instructions are received as to their disposition.

SUBSURFACE CONDITIONS

Regional Geology

The site is located in the Piedmont Region of Georgia. According to the Geology of the Greater

Atlanta Region (1984), the site is in the Powers Ferry Formation with underlying bedrock consisting of gneiss, amphibolite, and mica schist. The natural soils at the site consist primarily of residual materials formed from the in-place physical and chemical weathering of the underlying parent bedrock. The relative density of the residual soils is primarily dependent upon the degree of weathering, surface disturbance, groundwater action, and residual mineral bonding. The shear strength of residual soils is anisotropic and exhibits great variations from point to point. Soils with the flaky minerals oriented parallel to the potential shear plane and the slickenside surfaces have lower shear strengths.

The boundary between soil and rock is not clearly defined. A transitional zone called partially weathered rock (PWR) is normally found above the parent rock. PWR is defined for engineering purposes, as residual material with standard penetration resistances in excess of

100 blows per foot. Weathering is facilitated by fractures, joints, and the presence of less resistant rock types. Consequently, PWR and hard rock profiles are irregular and zones of

PWR or rock may occur within the soil mantle well above the general bedrock level. In some cases, boulders can be found in the upper soil matrix.

The natural geology in portions of the site has been modified in the past by grading that included the placement of fill materials. The quality of man-made fills can vary significantly, and it is often difficult to assess the engineering properties of existing fills. Furthermore, there is no specific correlation between N-values from Standard Penetration Tests performed in soil test borings and the degree of compaction of existing fill soils; however, a qualitative assessment of existing fills can sometimes be made based on the N-values obtained and observations of the materials sampled in the test borings.

Groundwater levels are irregular in the Piedmont Region. The surface of the groundwater table is largely dependent on the topography and is generally parallel to the ground surface. It can exhibit some distortions due to differences in vertical and horizontal permeability. The groundwater table can fluctuate several feet with seasonal rainfall.

Based on the online Soil Survey of Cobb County, Georgia, as prepared by the US Department of Agriculture Soil Conservation Service, a summary of the predominant soil types (within the upper 5 feet below original grade) at the site and their characteristics is included in the following table:

Soil Type Constituents Parent Material Internal

Drainage

Seasonal High

Water Table

(inches)

Cecil sandy loam

(CYB2)

Sands, Clays Residuum Well drained 80+

Madison sandy loam

(MgD2) Sands, Clays Residuum Well drained 80+

Madison and Pacolet soils (MsD3) Sands, Clays Alluvium Well drained 80+

Urban land (Ud) No information No information No information No information

Soil Conditions

Data from the soil test borings is included in the Appendix. The subsurface conditions discussed in the following paragraphs and those shown on the boring logs represent an estimate of the subsurface conditions based on interpretation of the boring data using normally accepted geotechnical engineering judgments. We note that the transition between different soil strata is usually less distinct than those shown on the boring logs.

Topsoil

Topsoil is a dark-colored surficial material with a high organic content and is generally unsuitable for structural support. Approximately 3 inches of topsoil was observed in the borings. Some variation in thicknesses should be expected across the site.

Fill Materials

Fill may be any material that has been transported and deposited by man.

Undocumented fill is considered any man placed materials with no moisture-density records from the time it was originally placed. Materials described as undocumented fill or possible fill were encountered in Borings B-1, B-2, and B-3 to depths of approximately

3 to 8 feet below the existing ground surface. The fill material generally consisted of medium dense clayey Sand or silty Sand. Standard Penetration resistances (N-Values) ranged from 13 to 27 blows per foot (bpf). Unsuitable materials were not visually observed in the soil samples recovered. However, unsuitable materials may exist in the undocumented fill and remain undetected between the widely spaced borings.

Residual Soils

Residual soil, formed by in-place weathering of the parent rock, was encountered in the borings below the ground surface and/or fill materials. The residual soil was generally described as loose to medium dense silty Sand (SM). N-Values ranged from 5 to 33 bpf.

Partially Weathered Rock

Partially weathered rock (PWR) is a transitional material between soil and rock, which retains the relic structure of the rock and exhibits Standard Penetration resistances greater than 100, but still can be penetrated by the power auger. PWR was not encountered in the borings performed to termination depths.

Auger Refusal Materials

Refusal is a designation applied to any material which cannot be further penetrated by the power auger and is normally indicative of a very hard or very dense material, such as boulders, rock lenses, or the upper surface of bedrock. Auger refusal was not encountered in the borings performed to termination depths.

Groundwater Conditions

Groundwater seepage was observed in the open bore holes of Borings B-1, B-2, B-3 and B-4 at depths ranging from 24 to 29 feet below existing grade during our fieldwork activities.

Observations for groundwater were made during sampling and upon completion of the drilling operations at each boring location. In auger drilling operations, the groundwater position can often be determined by observing water flowing into or out of the boreholes. Furthermore, visual observation of the soil samples retrieved during the auger drilling exploration can often be used in evaluating the groundwater conditions.

ANALYSIS AND RECOMMENDATIONS

Design Implications of Undocumented Fill

As previously noted, existing undocumented fill and possible fill materials were encountered in the borings. Although visual examination of the soil samples did not show evidence of extraneous or unsuitable materials, such as organics and debris, the presence and depth (up to

5.5 feet) of these undocumented fill materials presents a problem in quantifying the risk that unsuitable inclusions or low consistency soils may exist in areas of proposed new foundations.

If very soft soils or pockets of debris, organics, stumps, etc., exist within the fill and are not removed during construction, then localized excessive differential settlements could occur in response to new structural loads and the on-going process of volume change which may still occur in the fill. If such non-uniform settlements occur, then moderate distress could result.

Our experience indicates that well compacted structural fill typically is exhibits SPT N-values of

10 or more. Blow counts found in this undocumented fill are above that threshold value. Based on the lack of unsuitable material found in our borings and the moderately high N-values we suspect that the fill was placed in a semi-controlled to controlled manner as the fill was placed.

Consequently, we anticipate the fill material in the general area of the existing Firing Range structure may be suitable for the planned new construction without significant remedial action.

Although no unsuitable material were encountered in the undocumented fill, we recommend a grading allowance for unsuitables be set aside as a contingency and that the Owner anticipate some localized undercutting of unsuitable or soft materials may be necessary during foundation excavation. The actual extent and nature of the required remedial measures can be determined by ECS during footing observations/evaluations (hand auger borings) at the time of construction.

Foundation Design and Settlement

The maximum vertical column loads for the structure will be about 100 kips, and lateral loads on the main frame columns foundations will be approximately 140 kips. The foundations should be designed to resist both the vertical and lateral loading conditions. If the shallow foundations were being designed to resist just the vertical loads, then the shallow spread foundations could be designed for a net allowable soil bearing pressure of 3,000 psf on the existing fill or residual soil.

However, the foundation dimensions required to resist the lateral loads would be approximately

22’x22’x3’, and therefore would be prohibitively large. Consequently, the use of helical piles is anticipated to provide lateral resistance and thus reduce the foundation dimensions. Vertical helical piles typically have low lateral capacities. Therefore, lateral resistance can be provided with helical piles/anchors that are installed at an angle, or “battered”. Lateral capacities would be less than the axial capacities and would be dependent upon the batter angle as determined by the specialty foundation contractor. Please refer to the Helical Pile section of this report for more detail.

Even with the use of helical piles, we recommend that the foundation excavations be evaluated at the time of construction with the use of hand augers, Dynamic Cone Penetration (DCP) testing, and possibly test pits to identify and delineate any unsuitable material present at shallow depths. Typically, any unsuitable materials would have to be over-excavated if found during construction. Any over-excavation would normally extend laterally down and away from the actual footing dimensions at a 1H:1V slope so that the suitable structural backfill is within the footing’s zone-of-influence. Close quality assurance observation by ECS is required for this activity. However, the use of helical piles would likely reduce or eliminate the need for undercutting soft or unsuitable soils, if encountered.

To reduce the risk of foundation bearing failure and excessive settlement due to local shear or

"punching" action, we typically recommend that continuous footings have a minimum width of

1.5 feet and that isolated column footings have a minimum lateral dimension of 3 feet.

However, we note that additional vertical foundation capacity will likely be achievable with the use of the battered helical piles. As a result, it is possible that smaller column footing sizes may be achievable with less concern for foundation bearing failure.

In addition, footings should be placed at a depth to provide adequate bearing capacity. For this site, we recommend footing bottoms be placed at a minimum depth of 1.5 feet below finished grade.

We estimate that the new footings may be in close proximity to existing footings. Even with the use of helical piles, it is possible that new footing construction for the addition could induce settlement at the existing structures, possibly causing minor cracking and cosmetic distress. To minimize this effect, we recommend that new footings be structurally separated from old footings to allow for differential movement. Installing new footings below old footings should be avoided (unless underpinned or braced) due to potentially removing soils on which existing foundations are supported. Wherever possible, new footings should bear at the same level as old footings. Rigid connections between new and old construction should be avoided or at least delayed until late in the construction sequence.

Settlement of individual footings, designed in accordance with recommendations presented in this report, is expected to be within tolerable limits for new construction. Without helical piles, footings placed on engineered fill, residual soils, or existing fill soils constructed in accordance with the requirements outlined in this report, maximum total settlement would be expected to be less than 1 inch. Maximum differential settlement between adjacent columns or load bearing walls is expected to be half the total settlement. The maximum total and differential settlement would be expected to be less with battered helical piles.

The above settlement values are based on our engineering experience with similar soil conditions and the anticipated structural loading, and are to guide the structural engineer with his design. To minimize difficulties during the foundation installation phase, it is critical that

ECS be retained to observe the foundation bearing surfaces (confirm the recommended bearing pressures and lack of unsuitable material during construction).

Foundation Lateral Thrust - Helical Piles/Anchors

A helical pile or anchors system generally consists of one or more helix plates, attached to a shaft. The helix anchor is installed by applying torque to the shaft and screwing it into the soil.

The amount of torque required to screw the plate into place can be loosely correlated to the allowable load for the pile system.

Helical piles/anchors systems can resist lateral forces in either compression (pile) or tension

(anchor), depending on the direction of the pile/anchor shaft in comparison to the direction of the applied lateral forces. Helical piles/anchors can be screwed at downward battered angles as shallow at 12 degrees from horizontal. Installation lengths and batter angles can vary and would be dependent upon the soil conditions and the lateral forces being resisted.

Several of the appealing attributes of helical pile systems for this project are they do not require the mobilization of large and costly equipment for installation. Due to variable soil conditions, field adjustment of pile locations under foundations may be needed. If penetration of piles through dense layers becomes difficult, some pre-augering or local trench excavating with small backhoe may be needed to help penetrate piles in deeper layers. Any excavated material should be backfilled once the installation of pile system is completed.

Several proprietary helical pile systems are available in this area, including Chance

, Cantsink

Atlas and Ram Jack . The specialty foundation contractors below can assist in design and provide cost estimates. Local distributors and contacts are:

• Chad Costello (770-740-0400) of Atlas Piers of Atlanta, Inc.

• Cary Hannon (770-723-9887) of Foundation Technologies, Inc. for Chance Anchor

Foundation & Construction Products

• Andrew Carter (678-280-7453) of Cantsink of Atlanta

• Kent Walker (404-496-3328) of Ram Jack of Marietta

Depending on the type and size, typical helical pile capacities can range from 10 to 25 tons per pile. Based on the provided loading conditions, we recommend a series of 2 helical piles and 2 helical anchors at each column footing, with an allowable axial capacity of 25 tons (50 kips) per pile. The design batter angle and resulting lateral capacity should be determined by the specially foundation contractor. The following provides two types of Atlas Pier helical piles with typical 25 ton allowable capacities.

Helical piles with similar capacities are likely available from the other helical pile providers listed above.

From the test borings, the helical pile systems should penetrate into the moderately dense residual soils ranging from 20 feet (Boring B-4) to 30 feet (Boring B-2) feet below the ground surface. Piles may go deeper than 30 feet at Borings B-1 and B-3 where loose sands were still present at boring termination depths.

Depending on the depth of the helical pile system, special consideration should be given to rigidity of the shaft to ensure that buckling is not an issue. Post grouting of the pile could be used for increased capacities. Most proprietary systems have means of reinforcing the upper shaft to combat buckling and increase lateral resistance. In general, the soils at the site should be considered as cohesionless in the helical pile design.

We recommend one or more of the above Specialty Foundation Contractors be contacted to provide the best design for their specific product. At the appropriate time, ECS would be pleased to review any submittals for consistency with our design intent.

Ground Floor Slab Design

Whenever practical we recommend that the floor slab be isolated from the foundation footings so differential settlement of the structure will not induce shear stresses on the floor slab. Also, to minimize the crack width of any shrinkage cracks that may develop near the surface of the slab, we recommend welded wire mesh reinforcement be included in the design of the floor slab. The mesh should be in the top half of the slab to be effective.

We also recommend the slabs-on-grade be underlain by a minimum of 4 inches of granular material such as GAB or crusher run having a maximum aggregate size of 1.5 inches and no more than 10 percent of fines. This granular layer will facilitate the fine grading of the subgrade and help minimize the rise of moisture vapor through the floor slab. Prior to placing the granular material, the floor subgrade soil should be properly compacted, proofrolled, and free of standing water, mud, and frozen soil. Before the placement of concrete, a vapor barrier may be placed on top of the granular material to provide additional moisture protection. However, special attention should be given to the surface curing of the slab in order to minimize uneven drying of the slab and associated cracking. A modulus of subgrade reaction (K) of 75 pci may be used for slabs assuming the section meets the above requirements and the compaction requirements provided in the sections below are met.

Helical-Piles

SS 1.75 (Square Shaft) = 25 Tons

RS 3500.300 (Round Shaft) = 25 Tons

Soil Parameters

Advanced soil laboratory testing was not performed for this project. However, based on local experience and the site specific borings, the following soil parameters have been estimated for sandy or silty soils (SM, ML) for use in the design of footings and/or below grade walls:

• Coefficient of Earth Pressure “At Rest” (Kο) = 0.53

• Coefficient of Active Earth Pressure (Ka) = 0.36

• Coefficient of Passive Earth Pressure (Kp) = 2.77

• Moist Unit Weight of Soil = 120 pcf

• Angle of Internal Friction (φ) = 28 degrees

• Sliding Friction Resistance (concrete on soil) 0.45 x N *

*Where N is the vertical force component of the foundation system per linear foot.

Slopes

Our exploration did not include an analysis of slope stability for any temporary or permanent condition. However, within construction areas, we recommend temporary cut slopes without seepage be no steeper than 1.5H:1V and permanent cut or fill slopes without seepage be no steeper than 2H:1V for construction to 20 foot heights in the existing site soils. Slopes exceeding 20 feet in height or subject to seepage should be evaluated in more detail. In building and pavement areas, minimum top of slope setbacks of 10 feet and 5 feet are recommended, respectively.

During construction, temporary slopes should be regularly evaluated for signs of movement, seepage, or an unsafe condition. Soil slopes should be covered for protection from rain, and surface runoff condition. Stormwater runoff should be diverted away from the slopes. For erosion protection, a protective cover of grass or other vegetation should be established on permanent soil slopes as soon as possible.

CONSTRUCTION RECOMMENDATIONS

Subgrade Preparation

The subgrade preparation should consist of stripping vegetation, rootmat, topsoil, concrete, and any other soft or unsuitable material from the building area. We recommend the earthwork clearing be extended to a minimum of 10 feet beyond the building and pavement limits wherever practical. Stripping limits should be extended laterally an additional 1 foot for each foot of fill required at any location.

After stripping to the desired grade, and prior to fill placement or building construction, it is critical the stripped surface be evaluated by an engineer from ECS. Proofrolling using a loaded dump truck, having an axle weight of at least 20 tons should is recommend at that time to aid in identifying localized soft or unsuitable material which must be removed. Hand augers with

Dynamic Cone Penetrometer (DCP) testing can be used to delineate any unsuitable material if the area is not accessible to a dump truck and cannot be evaluated by proofrolling. Where unacceptable materials are encountered, they must be evaluated by ECS and may require remedial measures. Remedial options include undercutting and replacement with soil/rock, recompaction, partial over-excavation with geogrid placement, or drying.

Any below ground construction/utilities in the vicinity of the proposed building should be removed prior to the initiation of new construction. We suggest that available information regarding the existing utilities at the site be reviewed prior to construction.

Fill Placement

The preparation of fill subgrades as well as proposed building subgrades should be observed on a full-time basis by a representative of ECS to document that any unsuitable materials have been removed and that the subgrade is suitable for support of the proposed construction and/or fills.

Fill materials should consist of an approved material free of organic matter and debris, with rocks less than 6 inches and a Liquid Limit less than 40 and a Plasticity Index less than 20.

Unacceptable fill materials include topsoil, organic materials, lightweight material with a maximum dry density less than 95 pcf, and highly plastic silts and clays. Unsuitable materials removed during grading operations should be either stockpiled for later use in landscaped areas, or placed in approved disposal areas either on site or off site.

In general, the existing fill materials and residual soils appear generally suitable for re-use as structural fill if they are free from deleterious materials, such as organics and debris. Existing and off-site fill materials should be tested by ECS prior to use as structural fill.

The expanded footprint of the proposed building should be well defined including the limits of the fill zones at the time of fill placement. Grade control should be maintained throughout the fill placement operations. Fill operations should be observed on a full-time basis by a qualified soil technician from ECS to determine that minimum compaction requirements are being met.

A minimum of one compaction test per 2,500 square foot area should be tested in every one foot compacted lift placed. The elevation and location of the tests should be clearly identified and recorded at the time of fill placement.

Fill materials should be placed in lifts not exceeding 8 inches in loose thickness and moisture conditioned to within +/- 3 percent of the optimum moisture content to facilitate proper compaction. Controlled fill soils should be compacted to a minimum of 95 percent of the maximum dry density obtained in accordance with ASTM Specification D-698, Standard Proctor

Method.

The upper one foot of soil supporting structures, pavements, slabs-on-grade, sidewalks, should be “firm and unyielding” and any new fill compacted to a minimum of 98 percent of the maximum dry density obtained in accordance with ASTM Specification D-698, Standard Proctor

Method.

Additional Considerations

Exposure to the environment may weaken the soils at the footing bearing level if the foundation excavations remain open for too long a time. Therefore, foundation concrete should be placed the same day that excavations are dug. If surface water intrusion or exposure softens the bearing soils, the softened soils must be removed from the foundation excavation bottom immediately prior to placement of concrete. If the excavation must remain open overnight, or if rainfall becomes imminent while the bearing soils are exposed, we recommend that the foundations be covered or otherwise protected.

Positive site drainage should be maintained during earthwork operations, which should help maintain the integrity of the soil. Placement of fill on the near surface soils, which have become saturated, could be very difficult. When wet, these soils will degrade quickly with disturbance from contractor operations and will be extremely difficult to stabilize for fill placement.

Where unacceptable materials are encountered, they must be evaluated and may need to be undercut and replaced or improved by recompaction. On a previously filled site, the contractor must be especially alert for the possible existence of poor soil conditions that may become apparent during construction.

The surface of the site should be kept properly graded in order to enhance drainage of the surface water away from the proposed structure areas during the construction phase. We recommend that an attempt be made to enhance the natural drainage without interrupting its pattern.

The surficial soils contain fines, which are considered moderately erodible. Erosion and sedimentation shall be controlled in accordance with Best Management Practices and current

County and State NPDES requirements. At the appropriate time, we would be pleased to provide a proposal for conducting construction materials testing and NPDES services.

CLOSING

This report has been prepared in accordance with generally accepted geotechnical engineering practice. No warranty is expressed or implied. The evaluations and recommendations presented in this report are based on the available project information, as well as on the results of the exploration. ECS should be given the opportunity to review the final drawings and site plans for this project to determine if changes to the recommendations outlined in this report are needed.

Because undocumented fill is present on this site, the Owner must assess the relative risk that unacceptable material could have been buried in the proposed development area which was not detected in the widely spaced borings. It is critical that ECS be retained to perform foundation testing, proofrolling, and test pits on this site. If ECS is not retained for this extension of the field exploration, we can not be responsible for the performance of the foundations or site improvements. We would be pleased to provide an estimated cost for these services at the appropriate time.

This report is provided for the exclusive use of Toland-Mizell Architects and their project specific design team. This report is not intended to be used or relied upon in connection with other projects or by other third parties. ECS disclaims liability for any such third party use or reliance without express written permission.

Appendix I

SOURCE: USGS SCALE: 1 INCH = 0.6MI 9/16/2015

SITE LOCATION DIAGRAM

ATLANTA OFFICE

1281 KENNESTONE CIRCLE NE

SUITE 200

MARIETTA GA 30066

ECS PROJECT NO.10:8625

DOBBINS ARB - SMALL ARMS FIRING RANGE

COBB PKWY. S

MARIETTA GA

Figure No.

Appendix II

UNIFIED SOIL CLASSIFICATION SYSTEM (ASTM D 2487)

Major Divisions

Group Symbols

Typical Names Laboratory Classification Criteria

GW

Well-graded gravels, gravel-sand mixtures, little or no fines

Cu = D60/D10 greater than 4 Cc = (D30)

2/(D10xD60) between 1 and 3

C le an g ra ve ls

(L itt le o r no fin es

GP

Poorly graded gravels, gravel-sand mixtures, little or no fines

Not meeting all gradation requirements for GW d

GMa u

Silty gravels, gravel-sand mixtures

Atterberg limits below “A” line or P.I. less than 4

G ra

(M or e th an h al f o f c oa rs e fr ac tio n is la rg er th an

N o.

s ie ve s iz e)

G ra ve ls w ith fi ne s (A pp re ci ab le a m ou nt o f fin es

GC

Clayey gravels, gravel-sand-clay mixtures

Atterberg limits below “A” line or P.I. less than 7

Above “A” line with P.I.

between 4 and 7 are borderline cases requiring use of dual symbols

SW

Well-graded sands, gravelly sands, little or no fines

Cu = D60/D10 greater than 6 Cc = (D30)

2/(D10xD60) between 1 and 3

C le an s an ds

(L itt le o r no fin es

SP

Poorly graded sands, gravelly sands, little or no fines

Not meeting all gradation requirements for SW d

SMa u

Silty sands, sand-silt mixtures

Atterberg limits above “A” line or P.I. less than 4

C oa rs e-g ra in ed s oi e th an h al f o f m at er ia l i s la rg er th an N o.

S ie ve s

S ds e th an h al f o f c oa rs e fr ac tio n is sm al le r th an

N o.

s ie ve s ds w ith fi ne s

(A pp re ci ab le a m ou nt o f fin es

SC

Clayey sands, sand-clay mixtures

D et er m in e pe rc e nt ag es o f s an d a nd g ra ve l f ro m g ra in -s iz e cu rv e.

D ep en di ng o n p e rc en ta ge o f f in es fr ac tio n sm al le r th an

N o.

s ie ve s iz e)

, c oa rs e-g ra in ed s oi ar e cl as si fie d as fo llo w s:

Le ss th an p er ce nt

W

G

P

S W

, S P

M e th an pe rc en t

M

G C

S

M , S

C to pe rc en t

B de rli ne c as es r eq ui rin g du al s ym bo b

Atterberg limits above “A” line with P.I. greater than 7

Limits plotting in CL-ML zone with P.I. between 4 and 7 are borderline cases requiring use of dual symbols

ML

Inorganic silts and very fine sands, rock flour, silty or clayey fine sands, or clayey silts with slight plasticity

CL

Inorganic clays of low to medium plasticity, gravelly clays, sandy clays, silty clays, lean clays ilt s an d cl ay s (L iq ui d lim it le ss t ha n

OL

Organic silts and organic silty clays of low plasticity

MH

Inorganic silts, micaceous or diatomaceous fine sandy or silty soils, elastic silts

CH

Inorganic clays of high plasticity, fat clays ilt s an d cl ay s (L iq ui d lim it gr ea te r th an

0)

OH

Organic clays of medium to high plasticity, organic silts

F in e-gr ai ne d so ils e th an h al f m at er ia l i s sm al le r th an

N o.

S ie

H ig h ly

O rg a ni c so ils

Pt

Peat and other highly organic soils

Plasticity Chart

0 10 20 30 40 50 60 70 80 90 100

Liquid Limit

P la st ic it y

In de x

"A" line

CH

MH and OH

CL

ML and OL

CL-ML

a Division of GM and SM groups into subdivisions of d and u are for roads and airfields only. Subdivision is based on Atterberg limits; suffix d used when L.L. is 28 or less and the P.I. is 6 or less; the suffix u used when L.L. is greater than 28.

b Borderline classifications, used for soils possessing characteristics of two groups, are designated by combinations of group symbols. For example:

GW-GC,well-graded gravel-sand mixture with clay binder. (From Table 2.16 - Winterkorn and Fang, 1975)

REFERENCE NOTES FOR BORING LOGS

I. Drilling Sampling Symbols

SS Split Spoon Sampler ST Shelby Tube Sampler RC Rock Core, NX, BX, AX PM Pressuremeter DC Dutch Cone Penetrometer RD Rock Bit Drilling BS Bulk Sample of Cuttings PA Power Auger (no sample) HSA Hollow Stem Auger WS Wash sample REC Rock Sample Recovery % RQD Rock Quality Designation %

II. Correlation of Penetration Resistances to Soil Properties

Standard Penetration (blows/ft) refers to the blows per foot of a 140 lb. hammer falling 30 inches on a 2-inch OD split-spoon sampler, as specified in ASTM D 1586. The blow count is commonly referred to as the N-value.

A. Non-Cohesive Soils (Silt, Sand, Gravel and Combinations)

Density Relative Properties Under 4 blows/ft Very Loose Adjective Form 12% to 49% 5 to 10 blows/ft Loose With 5% to 12%

11 to 30 blows/ft Medium Dense 31 to 50 blows/ft Dense Over 51 blows/ft Very Dense

Particle Size Identification

Boulders 8 inches or larger Cobbles 3 to 8 inches Gravel Coarse 1 to 3 inches Medium ½ to 1 inch Fine ¼ to ½ inch Sand Coarse 2.00 mm to ¼ inch (dia. of lead pencil) Medium 0.42 to 2.00 mm (dia. of broom straw) Fine 0.074 to 0.42 mm (dia. of human hair) Silt and Clay 0.0 to 0.074 mm (particles cannot be seen)

B. Cohesive Soils (Clay, Silt, and Combinations)

Blows/ft Consistency Unconfined

Comp. Strength Qp (tsf)

Degree of Plasticity

Plasticity Index

Under 2 Very Soft Under 0.25 None to slight 0 – 4 3 to 4 Soft 0.25-0.49 Slight 5 – 7 5 to 8 Medium Stiff 0.50-0.99 Medium 8 – 22

9 to 15 Stiff 1.00-1.99 High to Very High Over 22 16 to 30 Very Stiff 2.00-3.00 31 to 50 Hard 4.00–8.00 Over 51 Very Hard Over 8.00

III. Water Level Measurement Symbols

WL Water Level BCR Before Casing Removal DCI Dry Cave-In WS While Sampling ACR After Casing Removal WCI Wet Cave-In WD While Drilling Est. Groundwater Level Est. Seasonal High GWT

The water levels are those levels actually measured in the borehole at the times indicated by the symbol. The measurements are relatively reliable when augering, without adding fluids, in a granular soil. In clay and plastic silts, the accurate determination of water levels may require several days for the water level to stabilize. In such cases, additional methods of measurement are generally applied.

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

SS

SS

SS

SS

SS

SS

SS

SS

Topsoil Depth [3"] (SC FILL) CLAYEY SAND, Contains Mica, Brown, Moist, Medium Dense

(SM) SILTY SAND, Contains Mica, Tan to Gray, Moist, Loose to Medium Dense

- Wet at 29'

END OF BORING @ 30'

CLIENT

Toland-Mizell Architects

JOB #

10:8625

BORING #

B-1

SHEET

PROJECT NAME

Dobbins ARB - Small Arms Firing Range

ARCHITECT-ENGINEER

SITE LOCATION

Cobb Pkwy. S, Marietta, GA

NORTHING EASTING STATION

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.

WL 29' WS WD BORING STARTED 09/01/15 CAVE IN DEPTH

WL(BCR) WL(ACR) BORING COMPLETED 09/01/15 HAMMER TYPE Auto

WL RIG CME 55 FOREMAN R.H. DRILLING METHOD HSADRILLING METHOD HSA

D E

P T

H

F T

S A

M P

L E

N O

S A

M P

L E

T Y

P E

S A

M P

L E

D

IS

T

(I N

R E

C O

V E

R Y

IN

SURFACE ELEVATION

DESCRIPTION OF MATERIAL

W A

T E

R L

E V

E L S

E L E

V A

T

IO

N

F T

B L O

W S

/6

10 20 30 40 50+

20% 40% 60% 80% 100%

1 2 3 4 5+

ENGLISH UNITS

BOTTOM OF CASING LOSS OF CIRCULATION

CALIBRATED PENETROMETER TONS/FT2

PLASTIC

LIMIT %

WATER

CONTENT %

LIQUID

LIMIT %

ROCK QUALITY DESIGNATION & RECOVERY

RQD% REC.%

STANDARD PENETRATION

BLOWS/FT970

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

SS

SS

SS

SS

SS

SS

SS

SS

Topsoil Depth [3"] (SC FILL) CLAYEY SAND, Brown, Moist, Medium Dense

(SC) CLAYEY SAND, Contains Mica, Brown to Black, Moist, Loose

(SM) SILTY SAND, Contains Mica, Tan to Gray, Moist to Wet, Loose to Dense

- Wet at 24'

END OF BORING @ 30'

16 18.1

CLIENT

Toland-Mizell Architects

JOB #

10:8625

BORING #

B-2

SHEET

PROJECT NAME

Dobbins ARB - Small Arms Firing Range

ARCHITECT-ENGINEER

SITE LOCATION

Cobb Pkwy. S, Marietta, GA

NORTHING EASTING STATION

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.

WL 24' WS WD BORING STARTED 09/01/15 CAVE IN DEPTH

WL(BCR) WL(ACR) BORING COMPLETED 09/01/15 HAMMER TYPE Auto

WL RIG CME 55 FOREMAN R.H. DRILLING METHOD HSADRILLING METHOD HSA

D E

P T

H

F T

S A

M P

L E

N O

S A

M P

L E

T Y

P E

S A

M P

L E

D

IS

T

(I N

R E

C O

V E

R Y

IN

SURFACE ELEVATION

DESCRIPTION OF MATERIAL

W A

T E

R L

E V

E L S

E L E

V A

T

IO

N

F T

B L O

W S

/6

10 20 30 40 50+

20% 40% 60% 80% 100%

1 2 3 4 5+

ENGLISH UNITS

BOTTOM OF CASING LOSS OF CIRCULATION

CALIBRATED PENETROMETER TONS/FT2

PLASTIC

LIMIT %

WATER

CONTENT %

LIQUID

LIMIT %

ROCK QUALITY DESIGNATION & RECOVERY

RQD% REC.%

STANDARD PENETRATION

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

SS

SS

SS

SS

SS

SS

SS

SS

Topsoil Depth [3"] (SM POSSIBLE FILL) SILTY SAND, Contains Mica, Tan to Gray, Moist, Medium Dense

(SM) SILTY SAND, Brown to Gray to White, Moist to Wet, Loose to Medium Dense

- Wet at 24'

END OF BORING @ 30'

CLIENT

Toland-Mizell Architects

JOB #

10:8625

BORING #

B-3

SHEET

PROJECT NAME

Dobbins ARB - Small Arms Firing Range

ARCHITECT-ENGINEER

SITE LOCATION

Cobb Pkwy. S, Marietta, GA

NORTHING EASTING STATION

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.

WL 27' WS WD BORING STARTED 09/01/15 CAVE IN DEPTH

WL(BCR) WL(ACR) BORING COMPLETED 09/01/15 HAMMER TYPE Auto

WL RIG CME 55 FOREMAN R.H. DRILLING METHOD HSADRILLING METHOD HSA

D E

P T

H

F T

S A

M P

L E

N O

S A

M P

L E

T Y

P E

S A

M P

L E

D

IS

T

(I N

R E

C O

V E

R Y

IN

SURFACE ELEVATION

DESCRIPTION OF MATERIAL

W A

T E

R L

E V

E L S

E L E

V A

T

IO

N

F T

B L O

W S

/6

10 20 30 40 50+

20% 40% 60% 80% 100%

1 2 3 4 5+

ENGLISH UNITS

BOTTOM OF CASING LOSS OF CIRCULATION

CALIBRATED PENETROMETER TONS/FT2

PLASTIC

LIMIT %

WATER

CONTENT %

LIQUID

LIMIT %

ROCK QUALITY DESIGNATION & RECOVERY

RQD% REC.%

STANDARD PENETRATION

S-1

S-2

S-3

S-4

S-5

S-6

S-7

S-8

SS

SS

SS

SS

SS

SS

SS

SS

Topsoil Depth [3"] (SM) SILTY SAND, Contains Mica, Tan to Gray, Moist, Loose to Medium Dense

END OF BORING @ 30'

CLIENT

Toland-Mizell Architects

JOB #

10:8625

BORING #

B-4

SHEET

PROJECT NAME

Dobbins ARB - Small Arms Firing Range

ARCHITECT-ENGINEER

SITE LOCATION

Cobb Pkwy. S, Marietta, GA

NORTHING EASTING STATION

THE STRATIFICATION LINES REPRESENT THE APPROXIMATE BOUNDARY LINES BETWEEN SOIL TYPES. IN-SITU THE TRANSITION MAY BE GRADUAL.

WL 28' WS WD BORING STARTED 09/01/15 CAVE IN DEPTH

WL(BCR) WL(ACR) BORING COMPLETED 09/01/15 HAMMER TYPE Auto

WL RIG CME 55 FOREMAN R.H. DRILLING METHOD HSADRILLING METHOD HSA

D E

P T

H

F T

S A

M P

L E

N O

S A

M P

L E

T Y

P E

S A

M P

L E

D

IS

T

(I N

R E

C O

V E

R Y

IN

SURFACE ELEVATION

DESCRIPTION OF MATERIAL

W A

T E

R L

E V

E L S

E L E

V A

T

IO

N

F T

B L O

W S

/6

10 20 30 40 50+

20% 40% 60% 80% 100%

1 2 3 4 5+

ENGLISH UNITS

BOTTOM OF CASING LOSS OF CIRCULATION

CALIBRATED PENETROMETER TONS/FT2

PLASTIC

LIMIT %

WATER

CONTENT %

LIQUID

LIMIT %

ROCK QUALITY DESIGNATION & RECOVERY

RQD% REC.%

STANDARD PENETRATION

B-2

S-2 3.50 - 5.00 18.1 SC FILL 48.1

Laboratory Testing Summary

Notes: 1. ASTM D 2216, 2. ASTM D 2487, 3. ASTM D 4318, 4. ASTM D 1140, 5. See test reports for test method, 6. See test reports for test method

Definitions: MC: Moisture Content, Soil Type: USCS (Unified Soil Classification System), LL: Liquid Limit, PL: Plastic Limit, PI: Plasticity Index, CBR: California Bearing Ratio, OC: Organic Content (ASTM D 2974)

Project No. 10:8625

Project Name: Dobbins ARB - Small Arms Firing Range

PM:

PE:

Printed On: Wednesday, September 16, 2015

Sample Source

Sample Number

Depth (feet)

MC1

Soil Type2 LL

Atterberg Limits3

PL PI

Percent Passing No. 200 Sieve4

Maximum Density

(pcf)

Moisture - Density (Corr.)5

Optimum Moisture

CBR

Value6 Other

Appendix III

Important Information About Your Geotechnical Engineering Report

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

The following information is provided to help you manage your risks.

Geotechnical Services Are Performed for Specifi c Purposes, Persons, and Projects Geotechnical engineers structure their services to meet the specifi c needs of their clients. A geotechnical engineering study conducted for a civil engineer may not fulfi ll the needs of a construction contractor or even another civil engineer. Because each geotechnical engineering study is unique, each geo-technical engineering report is unique, prepared solely for the client. No one except you should rely on your geotechnical engineering report without fi rst conferring with the geotechnical engineer who prepared it. And no one - not even you - should apply the report for any purpose or project except the one originally contemplated.

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

Do not read selected elements only.

A Geotechnical Engineering Report Is Based on A Unique Set of Project-Specifi c Factors Geotechnical engineers consider a number of unique, project-specifi c factors when establishing the scope of a study. Typical factors include: the client’s goals, objectives, and risk management preferences; the general nature of the structure involved, its size, and confi guration; the location of the structure on the site; and other planned or existing site improvements, such as access roads, parking lots, and underground utilities. Unless the geotechnical engi-neer who conducted the study specifi cally indicates otherwise, do not rely on a geotechnical engineering report that was:

• not prepared for you,

• not prepared for your project,

• not prepared for the specifi c site explored, or

• completed before important project changes were made.

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

• the function of the proposed structure, as when it’s changed from a parking garage to an offi ce building, or from alight industrial plant to a refrigerated warehouse,

• elevation, confi guration, location, orientation, or weight of the proposed structure,

• composition of the design team, or

• project ownership.

As a general rule, always inform your geotechnical engineer of project changes - even minor ones - and request an assessment of their impact.

Geotechnical engineers cannot accept responsibility or liability for problems that occur because their reports do not consider developments of which they were not informed.

Subsurface Conditions Can Change A geotechnical engineering report is based on conditions that existed at the time the study was performed. Do not rely on a geotechnical engineering report whose adequacy may have been affected by: the passage of time; by man-made events, such as construction on or adjacent to the site; or by natu-ral events, such as fl oods, earthquakes, or groundwater fl uctuations. Always contact the geotechnical engineer before applying the report to determine if it is still reliable. A minor amount of additional testing or analysis could prevent major problems.

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

A Report’s Recommendations Are Not Final Do not overrely on the construction recommendations included in your re-port. Those recommendations are not fi nal, because geotechnical engineers develop them principally from judgment and opinion. Geotechnical engineers can fi nalize their recommendations only by observing actual subsurface conditions revealed during construction. The geotechnical engi-neer who developed your report cannot assume responsibility or liability for the report’s recommendations if that engineer does not perform construction observation.

A Geotechnical Engineering Report Is Subject to Misinterpretation Other design team members’ misinterpretation of geotechnical engineer-ing reports has resulted in costly problems. Lower that risk by having your geotechnical engineer confer with appropriate members of the design team after submitting the report. Also retain your geotechnical engineer to review pertinent elements of the design team’s plans and specifi cations. Contractors can also misinterpret a geotechnical engineering report. Reduce that risk by having your geotechnical engineer participate in prebid and preconstruction conferences, and by providing construction observation.

Do Not Redraw the Engineer’s Logs Geotechnical engineers prepare fi nal boring and…